Life  History  of  Short leaf  Pine 
By  -  Wilbur  Reed  Malt o on 


Forestry 

SD397 

P617 

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JUljp  i.  39.  Hill  IGtbrarg 


Nortlj  (Carolina  ^tatp  Mniopraitg 

Forestry 
SD397 
P617 
M3 


LIBRARY 


S00426751    P 


THIS  BOOK  IS  DUE  ON  THE  DATE 
INDICATED  BELOW  AND  IS  SUB- 
JECT TO  AN  OVERDUE  FINE  AS 


LlPRAnV 


-M983 
AUG  18IS95 

'^^l  ^  1985,., 
mu  t     1996 
MAR  1  9  1998 

MAY  C  1  1986 


AUG  2  9  2005 


MAY  S  C 


(I 


Vi'^.n 


^,  BULLETIN    OF   THE 


No.  24i 


Contribution  from  the  Forest  Service,  Henry  S.  Graves,  Forester, 
July  21.  1915. 

(PROFESSIONAL  PAPER.) 

LIFE  HISTORY  OF  SHORTLEAF  PINE. 

By  WiLBUK  R.  Mattoon,  Forest  Examiner. 


CONTENTS. 

Page. 


Name  and  ideutifieation 

Geographical  and  economic  range. 

Character  of  stands 

■^'ze,  age,  and  habit 

Demands  apon  soil  and  climate. . . 


Ivight  requirements 

Reproduction 

Growth 

Causes  or  injury 

Yield 


Page. 
14 


NAME   AND   IDENTIFICATION. 

It  is  important  to  distinguish  clearly  the  true  shortleaf  pine^  (Pinus 
echinata  Mill.) — variously  known  throughout  portions  of  its  range  as 
"yellow,"  "old  field,"  "rosemary,"  "two-leaf,"  "heart,"  and  "spruce" 
pine — from  other  so-called  shortleaf  pines  of  the  Southern  States. 
Confusion  occurs  because  of  the  custom,  more  or  less  generally  pre- 
vailing throughout  the  South,  of  distinguishing  only  two  kinds  of 
pine,  shortleaf  and  longleaf.  Under  this  custom,  the  pine  most  com- 
monly included  with  shortleaf  is  loblolly  pine,-  slash  pine  being  classed 
in  similar  manner  as  longleaf  pine.  vShortleaf  is  most  readily  dis- 
tinguished from  loblolly  pine  by  means  of  differences  in  leaf  and 
cone,  described  on  page  7.  Other  pines  associated  with  short- 
leaf  are  the  smaller,  crooked-stemmed  scrub  pine  and  the  northern 
pitch  pine  which  seldom  forms  old-field  stands  and  grows  both  in 
wetter  and  colder  situations. 

1  Shortleaf  pine  was  first  described  botanically  by  Miller  in  ITtiS.  In  1803,  the  elder  Michaux  defined 
more  fully  the  specific  characteristics  of  the  species  under  the  name  of  Pinus  mitis,  widely  circulated  in 
his  work  on  American  forest  trees  and  largely  used  in  botanical  literature.  The  name  Pinus  echinata,  first 
given  to  the  tree  by  Miller,  was  not  taken  up  by  any  author  of  note  until  the  publication  of  Sargent's  Silva, 
Vol.  XI,  in  1897,  and  by  the  accepted  rule  of  priority,  this  is  the  correct  name  of  the  species. 

^ Pinus  taeda,  know  locally  by  various  names,  as  "old  field,"  "shortleaf,"  "swamp,"  "bull  pine,"  etc. 

Note. — This  bulletin  gives  in  detail  the  life  history  of  shortleaf  pine,  known  under  various  names  through- 
out the  South,  where  only  it  is  found  in  commercial  quantities. 
92233°— Bull.  244—15 1 


FOREST  RESOURCES  LIBRARY 
N.  C.  STATE  UNIVERSITY 


2  BULLETIN    244,    U.    S.    DEPARTMENT    OF    AGRICULTURE. 

GEOGRAPHICAL   AND   ECONOMIC   RANGE. 

Shortleaf  pine  occurs  in  24  of  the  States.  Its  geographical  range 
includes  all  the  States  east  of  the  Mississippi  River,  except  Wisconsin, 
Michigan,  and  New  England,  and  six  States  west  of  the  ^lississippi. 
It  extends  from  the  Hudson  River  VaUey  in  New  York^  south 
through  aU  the  Atlantic  and  Gulf  States  to  eastern  Texas  and  from 
West  Virginia  and  Ohio  southwestward  through  the  Ohio  and  Missis- 
sippi Valleys  to  Missouri,  Kansas,-  and  Oklahoma.  The  tree  is  dis- 
tributed over  more  than  440,000  square  miles.  This  is  much  larger 
than  the  range  in  the  United  States  of  white  pine,  its  nearest  com- 
petitor among  the  pines. 

Table  1. — Comparative  diMribution  of  eight  species  of  pines  havinrj  the  largest  ranges 
tnthin  the  United  States.'^ 


Species. 


Areaofdis-  States    rep- 


tribution. 


resented. 


Sq.  miles. 
440,000 
381,000 
360,000 
350,000 
317,  000 
300,000 
295. 000 
Longleaf  pine 171, 000 


Shortleaf  pine 

White  pine 

Pitch  pine 

Western  yellow  pine . 

Scrub  pine 

Red  pine 

Loblolly  pine. 


1  Areas  derived  from  Forest  Service  data  on  the  geographic  distribution  of  pines  in  the  I'nited  States, 
including  approximately  the  exterior  boundary  of  the  botanical  range. 

From  sea  level  shortleaf  pine  ranges  up  to  an  altitude  of  about 
3,000  feet  in  the  southern  Appalachians.  At  or  near  sea  level  it 
covers  more  than  1 1  degrees  of  latitude,  or  about  800  miles.  In  the 
North  the  species  is  confined  nearly  to  sea  level.  It  attains  its  best 
development  at  altitudes  of  600  to  1,500  feet  over  the  Piedmont  and 
at  400  to  1,000  feet  in  Arkansas.  In  both  these  localities  loblolly 
pine  reaches  only  to  altitudes  of  about  500  to  600  feet,  above  which 
shortleaf  is  the  only  important  southern  pine  up  to  3,000  feet  and 
the  only  conifer  except  scattering  juniper  above  about  700  feet  in 
Arkansas,  Missouri,  and  Oklahoma. 

The  commercial  range  of  shortleaf  pine  comprises  most  of  the 
botanical  range  except  that  portion  lying  in  the  States  north  of  Vir- 
ginia and  in  the  Ohio  River  basin.  It  includes  preeminently  the 
broad  Piedmont  region  lying  between  the  Appalachians  and  the 
Atlantic  coastal  plain  from  Virginia  to  South  Carolina;  the  northern 
half  of  Georgia,  Alabama,  Mississippi,  and  Louisiana;  aU  of  Arkansas; 
eastern  Oklahoma;  and  eastern  Texas.  Shortleaf  pine  is  the  only 
commercial  conifer  on  more  than  100,000  square  miles  of  upland 

1  Sargent.    Herbarium  notes.  May,  1913. 

2  Britton  and  Brown.    Flora  of  Northern  United  States  and  Canada.    Illustrated. 


LIFE    HISTORY    OF    SHORTLEAF    PINE.  6 

region  between  Virginia  and  northern  Alabama  and  Mississippi. 
The  total  area  of  its  commercial  range  covers  not  less  than  280,000 
square  miles.  The  production  reaches  its  maximum  over  the  gently 
rolling  and  hilly  country  of  the  Mississippi  basin  in  northern  Louisi- 
ana, most  of  eastern  Arkansas,  eastern  Oklahoma,  and  eastern  Texas. 
In  common  ^\^th  practically  all  other  commercial  pines,  the  economic 
range  of  shortlcaf  has  become  greatly  reduced,  and  over  the  extreme 
northern  part  it  has  been  almost  driven  out  by  close  utilization  and 


Fig.  1. — Botanical  and  commercial  range  of  shortleaf  pine. 


the  consequent  encroachment  of  hardwoods.  In  the  upper  portions 
of  the  Atlantic  coastal  plain  it  is  to  a  considerable  extent  being 
replaced  by  loblolly  pine  on  abandoned  fields.  The  early  clearing 
for  agriculture  of  the  lighter  and  better-drained  soils  greatly  decreased 
the  shortleaf  seed  trees  and  correspondingly  increased  the  relative 
proportion  of  loblolly  seed  trees,  which  were  left  growing  along  the 
watercourses  and  on  low  heavy  soils,  where  they  find  a  congenial 
home. 


4  BULLETIN   244,   U.    S.    DEPARTMENT   OF   AGRICULTURE. 

CHARACTER   OF   STANDS. 

PURE    STANDS. 

Shortleaf  is  very  well  adapted  for  growth  in  pure  stands,  and  it 
occure  extensively  in  tliis  fomi  of  forest.  The  stands  are  not  usually 
continuous  over  large  areas,  but  are  separated  by  mixed  stands  of 
pines  and  hardwoods.  Stands  of  pure  shortleaf  pine  once  covered 
a  much  larger  area  than  at  present.  It  is  dou])tful  whether  shortleaf 
is  now  found  in  pure  type  on  more  than  from  20  to  40  per  cent  of 
its  former  range. 

Mature  shortleaf  occurs  over  a  large  region  centermg  in  western 
Arkansas  and  northern  Louisiana.  This  is  the  last  extensive  region 
of  virgin  shortleaf  forest  left  in  the  gradual  progress  of  the  lumber 
industry  southward  and  westward  following  the  coast  line.  At  ele- 
vations of  400  to  1,200  feet  the  hilly  country  supports  heavy  stands 
of  timber,  which,  however,  are  being  lumbered  at  a  rapid  rate.  In 
the  higher  mountainous  regions,  including  the  southern  Appalachians 
from  1,000  to  2,000  feet  in  elevation  and  the  Arkansas  and  Ozark 
National  Forests,  the  warm  south-facing  slopes  are  generally  covered 
with  pine  in  pure  stands,  and  the  northerly  slopes  with  little  else 
than  hardwoods,  chiefly  oaks  and  hickories. 

A  considerable  proportion  of  the  pure  stands  of  shortleaf  is  found 
in  old  fields  fomierly  under  cultivation.  Here  the  factor  of  early 
competition  with  hardwoods  was  eliminated  and  the  pine  took  com- 
plete possession.  This  form  of  second-growth  forest  occm*s  exten- 
sively from  Virginia  southward  and  westward  throughout  its  entire 
commercial  range  and  aggregates  probably  more  than  68,000  square 
miles.^  It  represents  practically  all  the  land  within  the  shortleaf- 
pine  belt  that  has  at  any  time  been  cleared  and  subsequently  aban- 
doned. During  a  period  of  10  to  20  years,  commencing  in  1861,  a 
vast  acreage  of  such  lands  was  "turned  out"  all  through  the  South; 
but  the  process  of  "clearing  up,"  "working  out,"  and  "turning  back" 
land  has  been  in  connnon  practice  for  a  century  or  more  in  the  older 
pai'ts  of  the  Southern  States. 

MIXED    STANDS. 

CONIFERS. 

In  its  geograpliical  relation  to  the  other  eastern  pines  of  commercial 
importance,  shortleaf  occupies  a  position  characteristically  interme- 
diate between  white  and  Norway  pines  on  the  north  and  lobloUy 
and  longleaf  on  the  south.  Between  these  two  widely  separated 
groups  of  important  commercial  pines,  shortleaf  occupies  and  domi- 
nates a  broad  strip  of  country. 

1  Based  upon  general  forest  studies  in  practically  all  of  the  States,  and  detailed  examination  of  21  counties 
in  North  Carolina. 


LIFE    HISTORY    OF    SHORTLEAF    PINE.  5 

Altogether  10  different  species  share  in  varying  degree  the  range  of 
shortleaf.  Pond  and  slash  pines  and  spruce  pine  merely  overlap 
along  the  southern  margin,  but  pitch  and  scrub  pines  share  as  much 
as  one-third  to  one-half  the  botanical  range.  In  parts  of  Virginia 
and  North  Carolina,  scrub  pine  occurs  in  varying  proportion  in  the 
mixed  shortleaf  conifer  stands,^  particularly  in  old  fields,  and  it 
succeeds  in  getting  a  strong  foothold  in  the  poorer  soils,  dry  pastures, 
and  waste  places.  On  the  lower  or  warmer  side,  shortleaf  throughout 
practically  its  entire  range  associates  extensively  mth  loblolly  pine. 
In  this  association  the  two  maintain,  to  a  large  degree,  the  relation 
of  complementary  species,  loblolly  holding  the  heavier,  moist  soils 
and  shortleaf  the  drier  and  lighter  soils.  Valuable  and  extensive 
commercial  forests  of  this  character  occur  in  Georgia,  Alabama, 
Mississippi,  Texas,  and  especially  heavy  stands  in  Arkansas  and 
Louisiana.  Both  of  these  pines  to  some  extent,  and  particularly 
loblolly,  are  replacing  the  slower-growing  longleaf  on  all  situations, 
except  the  driest  and  most  sandy  soils,  tliroughout  their  region  of 
contact.^  In  the  longleaf  region  shortleaf  occurs  generally  in  groups 
or  smaU  stands  on  favorable  situations,  but  in  large  areas  west  of  the 
Mississippi  the  two  occupy  practically  the  same  soil  type,  and  in 
mixture  they  make  up  heavy  stands  of  maximum  development. 

HARDWOODS. 

A  large  number  of  broadleaf  species  are  associated  with  shortleaf 
through  its  extended  range.  Oaks  and  hickories,  however,  are  so 
constant  in  their  association  as  to  be  characteristic  in  many  of  the 
mixed  stands.  Over  the  Northern  Atlantic  States  chestnut  oak, 
yellow  oak,  and  red  oak  are  the  most  typical  associates.  From 
Virginia  southward  throughout  the  Piedmont  country,  lying  between 
the  coastal  plain  and  the  lower  slopes  of  the  mountains  up  to  2,500 
feet,  shortleaf  still  maintains  its  position  generally  as  the  dominant 
tree  in  mixture  with  the  upland  oaks  and  hickories.  The  primary 
associated  species  arc  yeUow  and  Spanish  oaks,  big-bud  and  bitternut 
hickories,  and,  on  the  thin  ridges,  post  oak  and  black-jack  oak.  The 
amount  of  shortleaf  in  the  mixture  varies  widely,  but  throughout  the 
eastern  range  represents  usually  from  35  to  60  per  cent  of  the  stand. 
In  the  hiUy  and  mountainous  parts  of  Arkansas,  the  mixed  shortleaf 
and  lobloUy  type  gives  way  at  elevations  above  about  400  feet  to 
heavy  stands  of  nearly  pure  shortleaf  up  to  about  1,000  feet,  whence 

'  Followmp  are  bctanical  and  common  names  of  pines  mentioned: 


Loblolly  pine  {Pinus  tacda  Linn.)- 
Longleaf  pine  (Pinus  paluslris  Mill.). 
Pitch  pine  (^Pinus  rigida  Mill.). 
Pond  pine  {Pinus  serotina  Michx.). 
Table  Momitain  pine  {Pinm  pungens  Michx.). 
*  Ashe,  ^y.  W.    Proceedings  of  the  Society  of  American  Foresters.    Vol.  V,  No.  1,  p. 


Norway  pine  {Pinus  resinosa  Ait.). 
Scrub  pine  {Pinus  virginiana  Mill.). 
Slash  pine  {Pinus  caribaea  MoreL). 
White  pine  {Pinus  strobus  Linn.). 


6  BULLETIX    '2U,    V.    R.    DEPARTMENT    OF    ACRICULTURE. 

the  sliortleaf-hardwood  mixed  forest  ascends  the  uiountaiii  slopes 
to  about  2,000  feet.  The  prevailing  associates  west  of  the  Mississippi 
River  are  oaks  and  hickories,  particularly  yellow  oak,  bitternut  and 
pignut  hickories;  on  the  dry  ridges  post  and  black-jack  oaks;  and 
in  the  fresher  soils  white  and  red  oaks,  big-bud  or  mocker-nut  hickory, 
and  red  gum/  The  commercial  importance  of  all  the  hardwoods 
typically  associated  with  shortleaf  is  comparatively  small,  except 
white  oak  in  the  region  of  its  better  development.  Several  inferior 
species,  including  pei'simmon,  sassafras,  and  dogwood,  are  nearly 
everywhere  represented  in  the  mixture. 

Table  2. — Forest  composition  of  the  Arkansas  and  Ozark  National  Forests.' 


Arkansas  National  Forest. 2 

Ozark  National  Forest.' 

Species. 

Total  stand. 

Per 

centage 

of 

total 

stand. 

Diameter. 

Total  stand. 

Per 
centage 

Average. 

Maxi- 
mum. 

of 
total 
stand. 

Shortleaf  pine 

Board  feet. 

1,500,000,000 

300,000,000 

100,000,000 

3.50,  000 

3,348,000 

96, 302,  000 

75.00 
1.5.  00 
.5.00 
.02 
1.67 
3.31 

Inches. 
18 
17 
16 
16 
16 

Inches. 
34 

36 

18 
22 

Boardfeet. 
108,  890, 000 
605, 925,  000 
252, 809,  000 
40,271,000 
63,248.000 
1,174,000 

10  15 

White  oak  

oti.  51 

Red  and  black  oak 

2i  57 

:i76 

Red  gum 

5.90 

Miscellaneous 

.  U 

Total               

2,000,000,000 

100.00 

1,032,317,000 

100.00 

»  Figures  for  the  Arkansas  Forest  secured  during  reconnaissance  in  1913.    Figures  for  Ozark  Forest  from 
Bulletin  106,  Forest  Service,  "  Wood-Using  Industries  and  National  Forests  of  Arkansas." 
2  Area  of  Forest,  750,000  a;cres. 
»  Area  of  Forest,  481,575  acres. 

The  percentage  of  shortleaf  is  relatively  small  in  the  Ozark,  which 
is  farther  north,  and  increases  outside  of  both  Forests  because  of  the 
lower  elevations  and  warmer  situations. 

Under  virgin  conditions  the  progressive  changes  within  this  mixed 
type  resemble  in  some  respects  those  that  occur  with  white  pine. 
By  the  thinnmg  or  removal  of  the  valuable  shortleaf  pme,  oppor- 
tunity has  been  afforded  for  the  more  rapid  reproduction  of  tolerant 
hardwoods  already  on  the  ground.  Thus,  some  territory  formerly 
dominated  by  shortleaf  in  mixture  is  now  held  almost  exclusively  by 
hardwoods. 


1  Names  of  hardwoods  mentioned: 
Big-bud  hickory  (Hicoria  alba  Britt.). 
Black  gum  {Nyssa  sylvatica  Marsh.). 
Black-jack  oak  {Quercus  marilai^ica  Muenchh.). 
Dogwood  (  Cornus  florida  Linn.). 
Chestnut  oak  (Quercus  prinus  Linn.). 
Persimmon  (Diospyros  virginiana  Linn.). 
Pignut  hickory  (Hicoria  glabra  Britt.). 
Post  oak  (.Quercus  minor  (Marsh.)  Sarg.). 


Red  gum  (Liquidambar  styraciflua  Linn.). 
Red  maple  (Acer  rubrum  Linn.). 
Red  oak  (Quercus  rubra  Limi.). 
Sassafras  (Sassafras  sassafras  (Linn.)  Karst.). 
Scarlet  oak  (Quercus  coccinea  Muenchh.). 
Spanish  oak  (Quacus  digitata  (Marsh.)  Sudw.). 
White  oak  (Quercus  alba  Linn.). 
Yellow  oak  (Quercus  velutina  Lam.). 


LIFE   HISTORY  OF   SHORTLEAF   PINE.  7 

SIZE,  AGE,  AND   HABIT. 

Over  much  of  its  range  the  average  height  attained  by  shortleaf  is 
between  80  and  100  feet,  and  in  regions  of  better  development 
between  100  and  120  feet,  with  a  maximum  of  about  130  feet.  Mature 
diameters  of  from  2  to  3  feet  are  most  common;  those  of  4  feet  are 
rare  except  in  trees  grown  in  the  open.  The  tree  commonly  reaches 
an  age  of  between  200  and  300  years,  a  maximum  of  about  400  years 
being  occasionally  attained. 

In  size,  shortleaf  holds  about  middle  ground  between  longleaf  and 
loblolly  pines.  Loblolly  gi-ows  to  an  equal  height  and  a  greater 
diameter,  but  is  not  so  straight  a  tree,  Longleaf  averages  a  little 
higher,  but  has  a  somewhat  smaller  trunk  at  maturity. 


A  long  clear  straight  bole  with  small  taper  and  short  crown  makes 
shortleaf  pine  almost  an  ideal  tree  for  the  saw.  These  characteristics 
are  so  much  more  pronounced  in  shortleaf  than  in  several  of  its  pine 
associates,  for  example,  pitch,  scrub,  and  loblolly  pine,  that  they 
serve  commonly  as  distinguishing  marks.  In  early  hfe  the  tree  has 
a  narrow  pyramidal  stem,  which  later  becomes  more  cylindrical  (Pis. 
I  and  II).  Tables  showing  the  form  or  taper  of  the  stem,  both  out- 
side and  inside  the  bark,  wdl  be  found  in  a  forthcoming  bulletin  on 
the  importance  and  management  of  shortleaf  pine.  These  include 
tables  for  North  Carolina  and  Arkansas,  showing  inside  bark  meas- 
urements at  intervals  of  8.15  feet  above  a  1.5  foot  stump  for  trees 
from  40  to  120  feet  in  height  and  of  corresponding  diameter  classes. 
The  tables  are  adapted  for  use  in  calculations  of  cubic  volume  of  saw 
timber  from  8  and  16  foot  logs,  allowing  0.3  foot  additional  length  for 
each  16-foot  log.  The  butt  taper  at  1-foot  intervals  of  trees  of  vari- 
ous diameters  is  also  shown,  and  there  is  a  table  of  tapers  outside  the 
bark  at  10-foot  intervals  above  the  ground  for  trees  from  40  to  90  feet 
in  height. 

CROWN   AND   BARK. 

A  short  crown  composed  of  numerous  small  branches,  foraiing  a 
narrow  pyramidal  head,  permits  of  the  close  density  which  charac- 
terizes shortleaf-pme  stands.  This  inherent  narrow  crown  habit  is 
well  shown  in  trees  grown  in  the  open,  where  it  is  conspicuous  even 
to  an  advanced  age.  Although  changes  take  place  in  the  relative 
demand  of  the  crown  for  light  after  the  period  of  maximum  height 
growth  (about  50  to  70  years),  the  change  in  the  general  shape  of  the 
crown  is  shght.  While  the  crown  of  longleaf  in  early  life  has  about 
the  same  outline  as  shortleaf,  though  loss  dense,  in  later  Hfe  it  broadens 
out  far  more.  Loblolly  maintains  a  much  wider  and  heavier  crown 
at  all  periods  of  life  than  either  of  the  other  important  southern 
pines.    This  habit  is  more  pronounced  on  the  drier  soils;  hence  in 


8  BULLETIN   244,   U.    S.    DEPAETMENT   OF   AnRICULTURE. 

the  upper  portions  of  its  range,  where  associated  witii  short  leaf,  this 
difference  in  outline  and  internal  branching  of  the  crowns  becomes 
striking  and  serves  as  a  distinguishing  characteristic. 

In  keeping  with  the  small,  close  crown  are  the  short,  slender  leaves 
of  shortleaf  pine.  The  leaf  characteristics,  together  with  the  cone, 
afford  the  best  means  of  identifying  the  species.  (Fig.  2.)  Special 
notice  of  this  is  essential,  because  confusion  prevails  generally  in  dis- 
tinguishing the  various  pines.  Shortleaf  belongs  distinctly  to  the 
two-leaf  group  of  pines.  On  the  more  vigorous  portions  of  the  crown, 
however,  three  leaves  in  the  bundle  are  not  uncommon.  The  leaves 
are  mostly  3  to  5  inches  long,  in  some  localities  appearing  en  masse 
of  a  slightly  bronzed  or  pale-green  color,  in  contrast  to  the  glaucous 
or  blue-green  color  in  other  locahties  or  regions.  Short  shoots  and 
colonies  of  sessile  leaf  bundles  are  often  scattered  along  the  trunk 
and  over  the  upper  sides  of  the  larger  branches.  These  are  found  on 
the  pitch  pine  of  the  North  and  the  pond  pine  of  the  South ;  hut  since 
they  occur  in  none  of  the  important  southern  timber  pines  except 
shortleaf,  they  serve  practically  as  a  characteristic  distinguishing 
shortleaf  from  both  loblolly  and  longleaf  pines.  The  size  of  the  cones 
("burrs")  aids  in  recognizing  shortleaf  when  otherwise  it  might  be 
confounded  with  loblolly  pine,  its  most  common  associate  in  the 
lower  soils.  The  small  cones  of  shortleaf  (from  1^  to  2h  inches  in 
length)  when  open  on  the  tree  appear  to  be  about  the  size  of  pigeon 
eggs;  those  of  loblolly  (from  3  to  5  inches  in  length)  about  the  size 
of  duck  eggs.  The  individual  scales  composing  the  cone  in  shortleaf 
are  armed  wdth  slender,  needle-pointed  prickles,  broken  off  more 
easily  than  the  stouter  persistent  prickles  of  loblolly  cones.  The  seed 
of  shortleaf  (described  on  p.  19)  is  likewise  much  smaller  than  that  of 
loblolly  pine. 

A  difference  in  the  bark  of  shortleaf  and  loblolly  is  readily  per- 
ceptible up  to  the  beginning  of  old  age.  The  bark  of  loblolly  is  on 
the  average  thicker,  more  deeply  furrowed  and  ridged,  and  somewhat 
darker  in  color  than  that  of  shortleaf.  After  maturity  these  differ- 
ences in  bark  become  less  marked,  or  disappear. 

RELATION   OF   CLEAR    LENGTH   TO   CROWN. 

Measurements  taken  in  shortleaf  stands  of  average  density  show 
much  regularity  in  the  relation  of  the  length  of  the  living  crown  to 
the  total  height  of  the  tree.  In  stands  about  10  feet  in  height  the 
depth  of  the  canopy  averages  5  feet,  or  one-half  the  height  of  the 
stand.  Above  this  height  the  canopy  gradually  becomes  propor- 
tionately shorter,  until  at  80  feet  clear  lengths  of  45  to  55  feet  are 
reached.  This  is  from  about  60  to  70  per  cent  of  the  total  height, 
varying  with  different  quahties  of  site.  The  crown  is  relatively 
longer,  in  proportion  to  the  total  height  of  the  tree,  on  the  poorer 
situations,  and,  conversel}^,  the  clear  length  of  the  stem  is  shorter. 


LIFE    HISTOEY    OF    SHORTLEAF    PINE. 


r^^-p^'^^/y 


Fig.  2.-Sliortleaf  pme  leaves,  seed,  cone  (burr),  and  seedling:  a.  Young  seedling;  b,  same  one  month  later; 
c,  seedling  at  end  of  first  season  showing  early  bundles  of  true  leaves;  d,  two-leaf  and  three-leaf  clusters; 
e,  branch  with  mature  closed  cones  (burrs);  f,  cone  scale  and  seed  with  wing  detached;  g,  mature  cone 
opened.    (Drawn  to  scale  from  actual  specimens.) 
92233°— Bull.  24-1— l.i 2 


10 


BULLETIN   244,   U.    S.   DEPARTMENT   OF   AGRICULTURE. 


Figure  3,  based  on  measurements  of  34  well-stocked  shortleaf  pine 
stands  in  Arkansas,  represents  graphically  the  proportion  of  clear 
length  to  crown  length  for  trees  of  various  heights  on  the  better  and 
poorer  quality  of  situations. 

The  lengths  of  the  crown  and  clear  stem  and  their  proportion  of 
the  total  height  of  the  tree  are  given  in  Table  3.  In  New  Jersey 
70-year-old  stands  65  feet  high  had  practically  the  same  actual  depth 
of  canopy  as  vigorous  stands  50  years  old  and  80  feet  in  height  in 
Arkansas.     The  proportion  of  clear  length  to  total  height  in  New 


SS     -^      33      32      ZS     /3       /O        S        C       ^-         S        /3       /S       2S      3/      '38      -^6 
C6ea.^ 6ert^&/v   of  Vree'6el.o>v  C/'oivn, — fee-b. 

Fig.  3.— Relative  proportions  of  clear  length  and  crown  depth  for  shortleaf  pine  of  various  heights  on  better 
and  poorer  qualities  of  site  in  Arkansas. 

Jersey  was  about  48  per  cent,  as  compared  with  70  per  cent  for  the 
better  stands  in  Arkansas. 

Table  3. — Clear  length  and  crown  length  of  dominant  trees  in  vell-slockeil  stands  of 
shortleaf  pine  in  Arkansas. 


Total  height  of  tree  (feet). 

Better  Quality  site. 

Poorer  quality  site. 

Clear  length. 

Crown  length. 

Clear  length. 

Crown  length. 

Feet. 
5 
10 
18 
25 
32 
39 
46 
55 
63 

Perct. 
50 
50 
60 
63 
64 
65 
67 

70 

Feet. 
5 
10 
12 
15 
18 
21 
24 
25 

Per  ct. 

50 
50 
40 
37 
313 
35 
33 
31 
30 

Feet. 
4 
8 
13 
19 
25 
31 
38 
46 
53 

Per  ct. 
40 
40 
43 
47 
50 
52 
54 
57 
60 

Feet. 
6 
12 
17 
21 
25 
29 
32 
34 
37 

Perct. 
60 

30               

57 

40                                                ... 

53 

50 

TO                                 ...           ... 

46 

SO 

43 

40 

CROWN   SPREAD   AND   TREE   DIAMETER. 

In  well-stocked  stands  of  shortleaf  pine  a  very  close  relationship  has 
been  found  to  exist  between  the  diameter  of  the  tree  at  breast  height 
and  the  diameter  of  the  crown.     This  relationship  is  strildng  in  its 


LIFE    HISTOBY    OF    SHORTLEAF    PINE. 


11 


constancy  and,  so  far  as  is  known/  has  never  before  been  found  to 
exist  in  any  Nortli  American  tree  species.  It  was  found  to  hold  true 
for  all  crown  classes  within  a  range  of  ages  from  20  to  80  years,  rep- 
resenting average  diameters  up  to  about  16  inches.  Indications 
point  to  this  relation  holding  true  beyond  80  years,  although  no  meas- 
urements in  pure  shortleaf  pine  have  been  made.  Later  measure- 
ments by  Prof.  H.  II.  Chapman,  of  Yale  Forest  School,  indicate  a 


?0 

a 

Ifl 

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^ 

IB 

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14 

*     »< 

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^ 

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.£  ^ 

f  f. 

in 

<■     1 

,  ^^  ■ 

> 

P 

9     l^» 

n^ 

»     5 

LEQENL 

; 

r 

: 

l,yr    o/d   S 
20 

hind    (Old 

(Fo 
(Old 

field)     /■» 

24 

rest)       10 

■tirJd)       24 

A 

/■ 

e 

31 
42- 

(Fc 
(.Old 

-est)       S3 
f,r:ld)      32 

16 

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|>'1 

■»■ 

5^" 
SO- 
A.^ragc   S. 

rr,ph    ^«« 

13 
12 

Us 

1    C/O)     2fl4 

rof,,l     559 

6  ^  10  12  14 

TREE  DIAMETER  BREAST  HIGH-INCHES 
Fig.  4.— Uelal  ion  of  crown  widtli  to  diameter  of  tree.    (f-:iiortleaf  pine,  1 1  to  GO  yea 


;  old,  in  Arkansas.) 


constant  relation  between  the  diameter  and  crown  in  mixed  short- 
leaf  and  lol)lolly  pine  stands  from  80  up  to  200  years;  also  recent 
deductions  from  yield  and  growth  data  of  red  spruce  show  a  definite 
relation  existing  between  basal  area  and  gi'owing  space  in  even-aged 
stands  between  20  and  100  years.^ 

The  evidence  from  which  the  conclusion  is  drawn  is  shown  in  figure 
4,  based  on  545  trees  on  25  sample  plots,  representing  16  different  ages, 

1  Determined  in  January,  1913,  from  measurements  taken  in  November  and  December,  1912. 
»  By  L.  S.  Murphy,  Forest  Service. 


12 


BULLETIN    2U,    U.    S.    DEPARTMENT    OF    AGRICULTURE. 


and  the  average  tree  on  each  of  14  other  sample  areas,  or  a  total  of 
559  trees.  All  the  trees  of  the  three  crown  classes  m  the  stand  and 
on  the  different  quahties  of  site  are  represented.  Under  the  influence 
of  all  these  different  factors,  which  are  considered  variables  in  mat- 
ters of  tree  growth  and  volume  increment,  the  size  of  both  diameter 
and  crown  spread  have  been  found  to  vary  uniformly  and  in  the  same 
direction.  This  intimate  relationship  between  tree  diameter  and 
crown  spread  is  apparently  an  expression  primarily  of  tolerance  or 
relative  demand  of  the  species  for  hght. 

Table  4  gives  the  average  crown  spread  in  feet  of  each  breast-high 
diameter  class  from  5  to  16  inches.  It  shows  a  perfect  regularity 
between  the  size  of  the  tree  and  the  space  occupied  by  its  crown, 
irrespective  of  age  and  vigor. 

The  table  shows  that  for  each  increase  of  1  inch  in  tree  diameter  the 
crown  spread  increases  1.4  feet  in  Arkansas  and  1.75  feet  in  New 
Jersey.  This  difference  in  rate  is  probably  due  to  the  effect  of  differ- 
ent climatic  conditions  upon  the  tolerance  of  the  species.  During 
earlier  life  up  to  about  15  years  the  relation  appears  to  be  in  the 
ratio  of  1  foot  of  crown  spread  to  each  inch  in  tree  diameter. 

This  law  of  growth  finds  practical  application  in  determining  for 
any  specified  diameter  class  the  total  number  of  trees  that  can  most 
profitably  be  grown  per  acre  in  a  weU-stocked  stand.  Since  diameter 
is  a  direct  function  of  age  in  any  given  quality  of  situation,  the  tree 
density  on  the  ground  at  any  desired  age  can  likewise  be  ascertained. 
Knowledge  of  this  sort  is  fundamental  in  working  out  problems  of 
thinning,  cutting,  and  final  yields  of  timber. 

Table  4. — Relation  of  tree  diameter  and  crown  diavuter  for  shortleaf  pine  trees  iti  fully 
stocked  stands  for  all  ages  from  20  to  80  years — Contrast  of  regional  difference  for 
Arkansas  and  New  Jersey. 


Crown  diameter. 

Favorable  region  (Arkansas). 

Unfavorable  region  (New 
Jersey). 

Tree  diameter  breast,  high  (inches). 

Crown 
diameter. 

Amount 

of 
increase. 

DifTer- 
ence  in 
crown 
diameter 
and  tree 
diameter. 

Crown 
diameter. 

Amount 

of 
increase. 

DilTer- 
enco  in 
crown 
diameter 
and  tree 
diameter. 

5 

Feet. 

5.2 

6.6 

8 

9.4 
10.8 
12.2 
13.6 
15 

16.4 
17.8 
19.2 
20.6 

Feet. 

Feet. 
4.8 
B.l 
7.4 
8.7 
10.05 
11.4 

14' 
15.  3 
16.6 
17.  95 
19.3 

Feet. 

3.25 

5 

6.75 

8.50 
10.25 
12 

13.75 
15.50 

Feet. 

Feet. 
2.  85 

6 

1.75 
1.75 
1.75 
1.75 
1.75 
1.75 
1.  75 

4.5 
6. 15 

8 

7.8 

11 

9.5 
11.21 
12.  85 

14.5 

16 

LIFE   HISTORY   OF   SHORTLEAF   PIXE.  13 

ROOT   SYSTEM. 

Having  strongly  developed  taproot  and  laterals,  the  tree  is  seldom 
thrown  by  wind  except  in  the  case  of  tornadoes.  This  root  system 
also  enables  the  tree  to  thrive  in  relatively  dry  situations.  Taproots 
14  feet  deep  have  been  found  on  8-year-old  saplings,  which  shows 
the  abihty  of  the  tree  to  search  for  moisture.  (PI.  I.)  This  root 
habit  may  account,  in  part  at  least,  for  the  wide  geographical  dis- 
tribution of  shortleaf  pine,  and,  within  much  of  its  range,  its  suprem- 
acy over  all  other  conifers,  except  red  juniper,  in  successfully  occupy- 
ing the  driest  upland  soils  and  exposed  ridges.  It  is  significant  that 
shortleaf  pine,  which  maintains  throughout  life  a  higher  tree  density 
in  pure  stands  than  any  other  eastern  or  southern  commercial  pine, 
possesses  inherently  both  a  narrow  crown  and  deep  root  system. 
Tlie  distribution  of  loblolly  pine  over  the  tideland  districts  and 
along  watercourses  and  the  absence  there  of  shortleaf  pine  is 
undoubtedly  due  to  an  ecological  effect  of  root  development  and 
iuherent  adaptation. 

DEMANDS  UPON   SOIL  AND  CLIMATE. 


Shortleaf  occui*s  on  a  wide  variation  of  soil  types,  ranging  from 
the  gravels  and  sands  to  stiff  clays.  In  respect  to  soil  moisture, 
however,  its-requirements  m  one  particular  are  more  exacting ;  namely, 
under  all  conditions,  shortleaf  avoids  very  poorly  drained  or  wet 
situations.  Its  home  is  essentially  on  the  better-drained  soils.  In 
New  Jersey  it  grows  on  the  low  ridges  of  gravelly  loam,  associated 
with  chestnut  oak.  Over  the  extreme  lower  portion  of  the  Atlantic 
coastal  plain,  from  North  Carolina  through  southern  Georgia,  Ala- 
bama, and  Mississippi,  its  occurrence  is  always  on  the  well-drained 
ridges  and  hummocks.  The  physiography  and  soil  types  of  the  Pied- 
mont region,  from  the  upper  coastal  plain  well  into  the  lower  slopes 
of  the  mountains,  are  favorable  to  its  vigorous  growth.  The  deep, 
well-drained,  gravelly  or  clayey  loam  soils  of  this  region  favor  short- 
leaf  but  discourage  loblolly,  which  is  much  inferior  in  abihty  to 
withstand  drought.  In  the  lower  shortleaf  range  toward  the  south- 
ern coasts  the  lighter  grades  of  sandy  soils  are  occupied  by  longleaf , 
which  possesses  .remarkable  tolerance  for  deep  and  very  dry  soil 
conditions. 

CLIMATE 

The  broadness  of  the  cHmatic  conditions  favorable  to  shortleaf 
pine  is  clearly  indicated  by  the  tree's  wide  geographical  range  The 
range  of  temperature  is  from  the  mean  annual  temperature  of  48° 
F.  in  northern  New  Jersey,  through  60°  in  central  Arkansas,  to 
70°  in  southeast  Texas.     Of  greater  significance  is  the  difference  be- 


14  BULLETIN    244,    U.    S.    DEPARTMENT    OP    AGEICULTURE. 

tween  the  midwinter  (January)  mean  of  26°  in  northern  New  Jersey 
and  the  midsummer  (July)  mean  of  84°  in  southeast  Texas.  Within 
its  geographical  range  occurs  a  total  temperature  range  of  134°  F., 
from  a  minimum  of  —22°  in  New  Jersey  to  a  maxinmm  of  112°  in 
northern  Louisiana.  The  length  of  the  growing  season  is  indicated 
approximately  by  the  period  during  which  killing  frosts  do  not  occur. 
In  New  Jersey  this  period  averages  only  five  months,  from  May  1  to 
October  1 ;  in  northern  Louisiana  it  is  a  little  less  than  eight  months, 
from  March  16  to  November  8.  There  is  a  variation  in  sno^\^'all  from 
an  average  of  40  inches  at  the  north  to  none  whatever  over  the  south- 
ern range  of  the  species. 

In  the  northeast,  the  45-mch  Ime  of  amiual  precipitation  closely 
parallels  the  northern  limit  of  shortleaf's  range,  and  the  line  marldng 
an  average  of  40  inches  of  precipitation  about  coincides  with  its 
southwestern  boundary  in  Kansas,  Oklahoma,  and  Texas.  Shortleaf 
advances  farther  into  this  region  of  low  relative  humidity  than  any 
other  pine,  and  in  its  advance  into  Texas  falls  behind  only  cypress 
and  eastern  red  cedar.  The  belt  of  maximum  development  of 
shortleaf — northern  Louisiana  and  Arkansas  and  the  southern 
Piedmont — coincides  strikingly  with  the  rainfall  zone  of  45  to  55 
inches,  or  an  average  of  50  inches. 

In  general,  shortleaf  pine  reaches  its  best  development  under  (1) 
a  mean  annual  temperature  of  about  55°  F.,  from  a  35°  average  for 
the  coldest  months  of  the  year  to  a  75°  average  for  the  warmest;  (2) 
an  annual  precipitation  of  45  to  55  inches,  distributed  through  at 
least  nine  months  of  the  year;  and  (3)  in  deep,  porous  or  w^ell-drained, 
clayey,  or  gravelly  loam.  In  less  favorable  conditions,  the  species 
shows  considerable  vigor  of  growth  over  regions  of  wide  variation  in 
temperature,  atmospheric  moisture,  soil  composition,  and,  exceptmg 
in  the  heavier,  poorly  drained  soils,  soil  moisture.  In  demands  upon 
both  moisture  and  heat,  shortleaf  is  clearly  the  least  exacting  of  the 
important  southern  pines,  which  may  be  put  in  the  following  order: 
Slash,  longleaf,  lobloUy,  shortleaf. 

LIGHT   REQUIREMENTS. 

Shortleaf  pine  requires  an  abundance  of  direct  overhead  light  fof 
development,  yet  at  the  same  time  it  possesses  to  a  remarkable 
degree  both  the  power  to  withstand  suppression  for  many  years  and 
the  capacity  of  rapid  recovery  following  suppression.  The  intimate 
relation  between  light  supply  and  growth  in  early  life  is  graphically 
shown  in  figure  5,  drawn  to  scale  from  an  11 -year-old  crowded  short- 
leaf-pine  stand.  The  adjacent  stands  cut  off  all  side  light  and 
slightly  reduce  the  overhead  supply.  The  height  growth  increases 
at  an  accelerated  rate  as  the  distance  from  the  adjacent  stand 
increases,  reaching  its  normal  level  of  22  feet  at  a  distance  approxi- 


LIFE    HISTORY   OF    SHORTLEAF   PIXE. 


15 


mately  the  same  as  the  height  of  the  marginal  trees.  IncidentaJly 
this  close  response  in  growth  to  varying  degrees  of  light  makes  short- 
leaf  a  good  recorder  of  unusual  climatic  or  other  events  which  strik- 
ingly alter  existing  light  relations.  Typical  examples  of  this  are 
given  on  page  32,  under  the  discussion  of  recovery  after  suppression. 
Because  of  its  inherently  narrow  cro^^l  and  medium  light  require- 
ments, the  density  of  shortleaf  stands  remains  high  to  a  relativel}^ 
advanced  age.  So  many  factors  enter  into  the  problem  that  it  is 
impossible  to  determine  the  absolute  position  of  shortleaf  in  the  scale 
of  light  requirements  without  a  much  greater  number  of  exact  meas- 
urements. To  compare  it,  however,  with  other  southern  pines,  under 
similar  conditions  of  soil,  heat,  moisture,  and  age,  shortleaf  through- 
out life  requires  less  light  for  development  than  longleaf,  does  not  in 
early  life  tolerate  shade  so  well  as  loblolly,  but  retains  longer  the 


Ai/erp.(pe   height   ZZ 


I 


fO      20     30     AO      SO      60 


0/SftUfC<S  /h  /=ee7^ 


60    SO    Ao    30   eo    /a    o 

>E 


Fig.  5.— Effect  of  light  supply  upon  height  growth,  shown  by  a  vertical  section  through  a  2-year-old  short- 
leafstand.  Fully  stocked,  even-aged  shortleaf  stand,  11  years  old  and  22  feet  high.  (Drawn  from  actual 
stand.) 

power  of  growth  under  limited  light  supply,  showing  this  retention  of 
power  by  a  relatively  later  and  slower  decrease  in  tree  density. 

NATURAL   THIN^fING    AND   STAND   DENSITY. 

The  dependence  of  shortleaf  on  a  full  supply  of  light  in  early  life  is 
seen  in  the  rapid  reduction  of  very  high  tree  density  in  natural 
unthimied  stands.  A  square  rod  of  8-year-old  saplings,  encroaching 
upon  a  cotton  field  in  Nevada  County,  Ark.,  contained  a  stand  of 
about  58,000  per  acre.  At  10  years,  as  many  as  25,000  to  40,000  trees 
per  acre  over  limited  areas  are  not  uncommon.  At  20  years  the 
normal  stand  contains  from  900  to  1,200  trees. 

In  fully  stocked  stands  natural  thimiing  progresses  very  rapidly 
durmg  the  first  decade  and  at  an  increasingly  slower  rate  during  the 
following  20  to  30  j'ears.  After  this  period  the  loss  of  trees  is  very 
noticeably  gradual  for  the  remainder  of  life.  Natural  thinning  is 
most  rapid  and  culminates  earliest  in  the  best  quaUty  of  situations 
both  from  a  regional  and  local  standpoint.     In  the  central  Mississippi 


16 


BULLETIN   244,   U.   S.   DEPARTMENT  OF  AGRICULTURE. 


Age20Vears 
(800  Trees  Per  Acre) 


Age33Vears 
(580  Trees  Per  Acre) 


Valley  region  the  first  general  period  ends  somewhere  between  the 
ages  of  40  and  50  years,  depending  upon  the  local  situation;  in  the 
central  Atlantic  coast  belt  apparently  between  55  and  70  years. 
Figure  6,  showing  progressive  stages  of  natural  thinning  and  cro"\\ai, 

classed  according  to 
age,  represents  actual 
numbers  of  trees  and 
outlines  of  crowns  as 
they  existed  in  four 
fully  stocked  stands 
in  Arkansas  measured 
for  growth  and  yield. 
The  20-year-old  stand 
contained  800  trees  per 
acre;  the  33-year-old 
stand,  580  trees;  the 
42-year-old  stand,  400 
trees;  and  the  52-year- 
old  stand,  320  trees 
per  acre. 

Shortleaf  pine  shows 
progressive  changes  in 
the  character  of  the 
forest  canopy  other 
than  the  mere  reduc- 
tion in  number  of  trees. 
These  changes  are  well 
illustrated  in  figure  6 
for  stands  from  20  to 
50  years  old.  In  early 
life  the  tree  crowTis  are 
approximately  circular 
in  outline  and  closely 
approach  each  other, 
leaving  very  little  un- 
occupied space.  At 
the  age  of  50  years, 
however,  the  tree  has 
become  less  tolerant, 
the  crowns  are  quite 
irregular  in  outline,  and  crown  isolation  leaves  relatively  large  light 
spaces  in  the  canopy.  The  slow  rate  of  natural  thimiing  after  about 
50  years  undoubtedly  is  accompanied  by  relatively  small  changes  in 
the  tolerance  of  the  tree.  The  climax  of  lateral  growth  or  spread 
of  the  branches  characteristic  of  the  species  seems  to  be  closely  ap- 


Age4-2  Years 
t400TreesPerAcre) 


Age52Year5 
(320Trees  Per  Acre) 


Fig.  6.— Progressive  change  in  tree  density  by  natural  thinning 
in  pure  even-aged  stands  of  shortleaf  in  Arkansas:  D,  Dominant 
classes;  I,  intermediate;  S,  suppressed  classes.  Areas,  33  by  06 
feet.    (Drawn  from  actual  stands.) 


3ul.  244,  U.  S.  Dept.  of  A^ 


Plate  I. 


j|.  244,  U.  S.  Dept.  of  Agriculture. 


Plate  II. 


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jl.  244,  U.  S.  Dept.  cf  Agricultu 


Plate  III. 


Bui.  244,  U.  S.  Dept.  of  Agriculture. 


Plate  IV. 


Fig.  1.— Shortleaf  Pine  Fire  Coppice  4  Years  Old  in  Foreground  from  6-Year- 
Old  Sprout  Parent  Stock.  A  Few  Trees  of  the  Former  Stand,  now  10 
Years  Old,  are  Seen  in  Center. 


Fig.  2.— Thrifty  Stand  of  Shortleaf  Pine  Reproduction,  3-Year-Old  Fif;E 
Coppice,  from  3-Year-Old  Seedlings  Parent  Stock.  Arkansas  National 
Forest. 


LIFE    HISTORY   OF    SHORTLEAF    PINE, 


17 


proached  at  about  the  age  oi  50  or  60  years  on  the  best  sites  and 
70  to  90  years  on  the  poorer  sites.  In  respect  to  the  number  of 
trees  per  acre  at  these  ages,  shortleaf  somewhat  exceeds  longleaf 
and  notably  surpasses  loblolly  on  similar  qualities  of  site.  At  ages, 
ranging  mostly  from  175  to  225  years,  natural  thinning  of  stands, 
due  to  old  age  and  overmaturity,  goes  on  at  a  more  rapid  rate.  This 
is  closely  associated  with  the  incoming  of  the  new  generation  and  the 
sudden  and  rapid  increase  in  numbers  per  acre. 

The  number  of  trees  per  acre  in  well-stocked  stands  decreases  as 
the  quality  of  the  site  improves.  At  20  years,  well-stocked  stands 
in  the  Arkansas  region  have  usually  from  1,000  to  1,300  trees  per  acre; 
in  North  Carolina,  1,400  to  1,800;  and  in  central  New  Jersey,  1,800 
to  2,400.  In  general,  this  regional  difference  holds  good  for  several 
decades;  so  that  at  50  years  well-stocked  unthinned  stands  have 
approximately  300,  355,  and  500  trees  per  acre,  respectively,  in  the 
above  three  regions.  The  relation  of  the  density  to  the  quahty  of 
situation,  both  in  one  locality  and  in  widely  separated  regions, 
appears  to  be  constant  and  regular.  The  difference  in  densities  in 
normal  or  well  stocked  stands  in  North  Carolina  and  Arkansas  is  well 
shown  by  the  contrast  between  Table  5  and  Table  6. 

Table  5. — Number  of  shortleaf  trees  per  acre  in  stands  of  different  densities  in  Arkansas.^ 


Age  (years). 


Under- 

Well 

Over-" 

stocked. 

stocked. 

stocked. 

840 

1,130 

1,540 

475 

600 

1,000 

290 

400 

550 

210 

300 

400 

170 

250 

325 

140 

215 

280 

100 

185 

250 

80 

145 

185 

80 

128 

175 

75 

118 

160 

Age  (years). 


Under- 

Well 

stocked. 

stocked. 

75 

115 

70 

110 

65 

105 

65 

102 

60 

100 

60 

100 

60 

100 

55 

55 

95 

Over- 
stocked. 


I  Based  on  measurements  in  38  even-aged  stands.  The  number  of  trees  per  acre  vary  quite  widely  in 
each  case  in  accordance  with  the  quality  of  the  situation,  and  the  numbers  should  be  considered  approxi- 
mate rather  than  exact. 


Table  G. — Number  of  trees  per  acre  for  well-stocked  shortleaf  stands  in  North  Carolina. 


Age  (years).        j  Q"f  ^y 

Quality 

Quality 

Age  (years). 

Quality 

Quality 

ftuaj.,. 

20 

1,000 
675 
510 
410 
340 
280 
235 

1,635 
1,095 
765 
600 
509 
420 
355 

2,4.50 

1,880 

1,405 

1,045 

795 

655 

550 

200 
165 
140 
120 
100 
90 

310 
270 
230 
205 
180 
155 

30 

65 

370 

35 

70 

330 

40 

50 

92233^ 


'  Based  on  measurements  of  80  sample  plots;  area,  21.6  acres. 
-Bull.  244—15 3 


18  BULLETIN   244,   U.    S.    DEPARTMENT   OF   AGEICULTURE. 

As  a  result  of  repeated  burnings  the  density  of  natural  stands  is 
usually  very  variable.  Occasionally  second-growth  stands  have  been 
protected  by  surrounding  cultivated  fields  and  the  watchfulness  and 
care  of  their  o\^Tiers.  Such  stands  show  striking  regularity  of  tree 
density  and  much  quicker  wood  production  than  unprotected  stands, 
which  is  due  to  the  influence  of  a  protective  mulch  consisting  of  leaves 
C'pine  straw"),  twigs,  and  bark. 

REPRODUCTION. 

Few  of  the  valuable  pines  in  the  United  States  reproduce  as  vig- 
orously as  shortleaf .  The  regeneration  is  accomplished  by  seed  and 
by  complete  sprouting  during  the  period  of  early  life  when  the  tree 
is  most  susceptible  to  severe  injury.  Reproduction  by  means  of  nat- 
m-al  seeding  is  successful  and  heavy,  because  of  the  frequent  and  full 
seed  crops,  the  lightness  and  short  germinating  period  of  the  seed, 
and  the  high  resistance  of  the  seedling  to  unfavorable  conditions  of 
temporary  shade  and  drought. 

Abandoned  fields  and  openings  made  by  lumbering,  windfall  (in  the 
tornado  belt  west  of  the  Mississippi),  and  fires  are  quickly  occupied 
by  shortleaf  pine.  Ten  representative  counties  in  western  North 
Carolina  contain  393,670  acres  of  old-field  stands  of  mostly  pure  short- 
leaf  pine.  This  is  14  per  cent  of  the  total  area,  or  27  per  cent  of  the 
forested  area,  of  the  counties.  Such  old-field  stands  characterize  the 
forest  lands  of  the  upland  regions  from  Virginia  southward  and  west- 
ward throughout  the  range  of  the  species.  The  extensive  pineries 
near  Lakewood,  N.  J.,  are  mostly  pure  stands  of  shortleaf  C' two- 
leaf ")  pine  of  similar  origin.  (PI.  II.)  In  mixture  with  the  inferior 
pitch  pine  in  New  Jersey  and  loblolly  pine  in  the  lower  or  outer  por- 
tions of  the  shortleaf  range,  it  has  not  successfully  held  its  former 
place  of  importance.  The  cause  lies  chiefly  in  the  much  closer  utili- 
zation of  the  shortleaf  and  the  resulting  relatively  greater  abundance 
of  seed  trees  of  the  associated  species.  In  the  southern  mixed  hard- 
wood forest  there  has  been  a  notable  extension  of  the  importance  and 
commercial  range  of  shortleaf.  This  has  been  due  to  the  successive 
clearing,  working,  and  "turning  out"  of  fields  and  to  the  extensive 
ranging  of  hogs.  The  hogs  consume  practically  aU  of  the  oak  and 
hickory  seed  and  at  the  same  time  prepare  excellent  seed  beds  for 
shortleaf  pine  by  uprooting  soil  and  humus  in  the  fall  of  the  year. 
Some  seedlings,  of  course,  are  later  destroyed  by  the  same  process. 
The  results  of  these  two  agencies,  operative  for  periods  of  75  to  200 
years,  have  been  cumulative  and  have  produced  marked  changes  in 
the  composition  and  density  of  the  forest  in  various  parts  of  the 
South. 

On  the  National  Forests  of  Arkansas  natural  reproduction  is  heavy 
except  on  the  cool  northern  exposures,  and  the  encroachment  of 


LIFE    HISTORY   OF    SHOETLEAF    PIXE.  19 

shortleaf  pine  into  the  oak  and  hickory  tj-pe  is  particularly  notice- 
able. Fresh  openings  become  fully  stocked  usually  during  the 
first  four  years;  and,  normally,  in  the  mixed  pine-and-hardwood 
type,  groups  of  pure  young  pine  of  a  few  prevailing  age  classes  are 
numerous. 

SEED. 

The  seed  of  shortleaf  is  very  small,  varying  usually  from  50,000  to 
70,000  to  the  pound.  The  cones  which  produce  them  are  among 
the  smallest  for  all  pines — from  1^  to  2|  inches  in  length.  They 
persist  on  the  trees  for  periods  of  about  four  years  on  vigorous  shoots 
to  seven  or  eight  3^ears  on  suppressed  portions  of  the  crown.  Ripen- 
ing in  early  autumn,  the  seeds  fall  by  the  middle  of  November  and 
he  dormant  during  the  winter.  Germination  usually  takes  place 
during  March  or  April.  In  ordinary  seed  years  the  seed  averages 
50  to  60  per  cent  germination,  varying  quite  widely  below  this  stand- 
ard in  unfavorable  seasons  and  with  unhealthy  or  old-aged  trees. 
One  tree  280  years  old  had  a  full  crop  of  cones  bearing  apparently 
good  seed.  The  germinative  power  of  shortleaf  pine  is  retained  to 
a  large  degree  for  several  years.  Seed  of  the  1911  seed  crop,  kept  at 
ordinary  living  temperatures,  gave  56.8  per  cent  germination  in  the 
spring  of  1914.  The  seedlings,  however,  were  apparently  somewhat 
lower  in  vigor  than  those  grown  from  fresh  seed. 

The  seed  of  the  shortleaf  has  some  advantages  over  seeds  of  other 
species.  A  marked  abihty  to  germinate  successfully  in  grass  and 
leaf  litter,  as  compared  with  other  southern  pines,  has  been  ob- 
served.^ This  is  in  line  with  the  inherent  capacity  of  the  species  to 
thrive  on  the  lighter  upland  soils  deficient  in  soil  moisture.  The 
very  small  size  of  the  seed  gives  it  an  advantage  over  larger  seed 
in  quickly  reaching  mineral  soil.  By  means  of  a  relatively  large 
wing  the  seed  is  readily  borne  by  the  wind.  A  breeze  will  carry 
seed  a  distance  of  from  2  to  5  times  the  height  of  the  tree;  and  strong 
winds  will  carry  it  from  one-eighth  to  one-fourth  of  a  mile. 

Seed  is  produced  both  abundantly  and  regularly.  Full  crops 
occur  at  an  average  interval  of  about  three  years,  with  intermediate 
or  partial  crops  almost  every  season.  In  a  typical  region  of  the 
Arkansas  National  Forest,  during  a  period  of  13  years  commencing 
in  1901,  shortleaf  pine  bore  four  full  seed  crops,  seven  partial  crops, 
and  failed  entirely  during  two  seasons.^  The  years  of  abundant 
seed  were  1902,  1907,  1910,  and  1913;  1903  and  1909  were  blank 
years,  and  the  others  intermediate.  Thrifty  trees  with  good  fight 
supply  begin  to  produce  seed  at  about  20  years.  Exceptional  trees 
have  been  noted  with  cones  at  16  years.     In  open  or  mixed  forest 

'  Proceedings  of  the  Society  of  American  Foresters,  Vol.  V,  No.  1,  "Loblollj-  and  Shortleaf  Pines,"  by 
W.  v.  Ashe. 
'  Record  of  seed  crops  determined  by  study  of  crowns  in  a  large  logging  area,  Womble,  Ark. 


20  BULLETIN    244,    U.    S.    DEPARTMENT   OF   AGEICULTURE. 

stands  seed  is  produced  at  intervals  tliroiighout  life  after  about  the 
thirtieth  year.  In  crowded  stands  seed  production  is  confined  to 
the  larger  dominant  trees  and  is  deferred  until  about  40  years. 

SPROUT   OR   COPPICE   REPRODUCTION. 

Shortleaf  pine  sprouts  vigorously,  and  thus  reproduces  itself  if 
killed  back  during  the  period  of  early  life.  This  period  fortunately 
is  the  time  of  greatest  susceptibility  to  injury  both  by  fire  and  various 
mechanical  agencies.  Its  range  over  the  drier  uplands  is  coincident 
vnth  a  region  of  frequent  forest  fires,  yet  it  is  saved  by  notably 
abundant  reproduction  practically  every^vhere.  Of  the  important 
commercial  pines  in  the  United  States  shortleaf  alone  possesses  tliis 
capacity  of  complete  reproduction.^  A  field  investigation  in  1912-13 
showed  clearly  that  comparatively  very  few  seedlings  reach  ages  of  3 
to  6  years  without  being  burned  back,  and  that  most  forest  stands 
have  passed  through  this  experience  on  repeated  occasions. 

It  has  been  found  possible,  although  somewhat  difficult,  to  trace 
the  history  of  most  stands  and  determine  definitely  their  origin, 
whether  of  direct  seedhng  or  coppice  growth.  Thus,  the  majority 
of  all  standing  shortleaf  timber  examined  in  various  portions  of 
Arkansas  was  found  to  be  of  coppice  origin.  In  abandoned  fields 
fire  less  frequently  sweeps  over  young  stands  because  of  the  fu'e  pro- 
tection afforded  by  the  naked  soil.  In  spite  of  this,  many  old-field 
stands  have  suffered  from  at  least  one  fire.  Observation  in  Georgia, 
South  Carolina,  Virginia,  and  New  Jersey  showed  that  similar  con- 
ditions exist  throughout  the  geographical  range  of  the  species.  The 
property  of  sprouting  accounts  for  the  remarkable  aggressiveness  of 
shortleaf  pine  over  the  region  in  the  South  most  endangered  by  fire. 
Second-growth  forests  of  the  Piedmont  and  Appalachian  regions  have 
been  subject  to  frequent  fires  during  more  than  a  century.  As  a 
general  law,  it  may  be  stated  that,  in  any  specified  locality,  the  pro- 
portion of  shortleaf  pine  of  seedling  origin  varies  inversely  as  the 
frequence  and  general  prevalence  of  fires.  Stands  of  direct  seedling 
origin  are  on  the  whole  of  insignificant  area,  because  there  are  few 
localities  protected  against  fire  by  natural  barriers  or  by  man.  In 
one  locality  of  optimum  shortleaf  development  in  Pike  County,  Ark., 
the  only  stands  of  direct  seedling  origin  found  were  located  in  low, 
moist  situations  where  burnings  have  been  infrequent.  Obviously 
the  perfection  of  vigorous  reproduction  by  coppice,  though  limited 
to  early  years,  is  of  high  importance  in  the  profitable  management 
of  a  forest  species.  Since  the  occurrence  of  a  commercial  coniferous 
forest  largely  of  coppice  origin  is  very  unusual  in  any  other  species, 
a  discussion  of  the  function  of  coppicing,  the  sprouting  capacity  of 
the  tree,  and  the  way  in  which  the  sprouts  are  produced  is  of  interest. 

'  other  pines  which  to  a  greater  or  less  degree  sprout  when  young  are  pitch  pine  (P.  rigida),  pond  pine 
(P.  serotina),  and  Pinus  cWmahvxina  along  the  Mexican  border. 


LIFE    HISTOEY   OF    SHORTLEAF    PIXE. 


21 


EXTENT   AND   NATURAL   LIMITATIONS. 

In  open-grown,  vigorous  stands,  shortleaf  successfully  coppices  up 
to  about  the  eighth  year,  and  in  slow-growing,  crowded,  or  shaded 
stands,  to  the  tenth  or  twelfth  years.  The  upper  limit  of  size  at 
which  coppicing  may  take  place  ranges  from  diameters  near  the 
ground  of  3  to  4  inches  for  vigorous  individuals  down  to  2  to  3  inches 
for  trees  of  slow  growth.  Thus  the  chief  limitation  seems  to  be  age, 
modified  by  the  general  vigor  and  size  of  the  individual  stem. 

Withm  these  limits  shortleaf  is  known  to  coppice  repeatedly. 
Regions  of  frequent  fires  afford  opportunities  to  observe  the  effects  of 
repeated  burning  to  the  ground  upon  younger-aged  stands.  Figure  7 
shows  diagrammatically  a  fully  stocked  stand  in  Arkansas,  composed 


Fig.  7.— Vertical  section  through  three  successive  generations  of  shortleaf  pine  fire  coppice.    PikeCounty, 
Ark.    (Drawn  from  actual  stand.) 

of  three  successive  generations  of  coppice  resulting  from  fires  in 
1902,  1904,  and  1910.  Each  age  class  was  regular  and  normally 
stocked.  The  heights  averaged  17  feet  for  the  10-year-old,  11.5  for 
the  8-ycar-old,  and  2.5  feet  for  the  2-year-old  stand.  Similar  suc- 
cessive generations  of  coppice  are  commonly  met  throughout  all  the 
shortleaf  region.  Around  the  margin  of  a  young  stand,  surface 
fires  burn  freely,  fed  by  the  better  growth  of  grass  and  light  dry 
materials  deposited  by  the  wind;  while  farther  within  the  stand  there 
is  less  ground  litter,  and  the  shaded  surface  is  often  too  moist  to  burn 
in  the  cool  season  when  fires  prevail. 

The  number  of  successive  generations  of  sprouts  that  can  be  pro- 
duced from  an  original  parent  seedling  is  not  known.  Young  coppice 
of  the  second  generation  of  sprouts  is  readily  identified  under  close 
observation.     It  occurs  abundantly  except  in  old-field  stands.     Three 


22  BULLETIN    244,   U.    S.    DEPAETMENT   OF   AGRICULTURE. 

successive  generations  of  coppice  have  been  definitely  identified ;  but 
beyond  tliis,  evidences  of  the  past  history  of  the  tree  become  greatly 
obscured.  In  the  third  generation  of  sprouts  the  rate  of  height 
growth  appears  to  be  undiminished.  Practically  all  of  the  root 
system  is  utilized  by  the  new  generation.  As  an  effect  of  the  root 
energy  and  stored-up  food,  the  rate  of  early  height  growth  is  remark- 
ably rapid  and,  within  limits,  increases  with  the  age  of  the  parent 
tree  when  cut  or  burned  back.  As  a  rule,  during  the  first  two  to  four 
years,  depending  upon  the  age  of  the  parent,  the  sprouts  make  up 
completely  for  the  previous  loss  of  time  in  growth.  The  most  rapid 
height  growth  observed  was  in  a  4-year-old  fire  sprout  stand,  many 
trees  being  from  5  to  8  feet  in  height  and  the  tallest  9.6  feet.  The 
growth  in  height  of  thrifty  stands  of  fire  coppice,  based  on  measure- 
ments of  both  trees  and  whole  stands  up  to  18  years  old,  is  showTi  in 
Table  6.  The  age  at  which  trees  of  sprout  origin  grow  at  approxi- 
mately the  same  rate  as  seedling  trees  is  not  precisely  known.  Under 
average  conditions  this  point  is  perhaps  between  the  fifth  and  ninth 
years.  In  general,  the  great  acceleration  in  growth  in  fire  sprouts 
takes  place  at  approximately  the  same  rate  in  diameter  and  volume 
as  in  height. 

CAUSE   AND  METHOD. 

Fire  and  cutting  are  the  chief  external  causes  for  the  sprouting  of 
shortleaf  pine.  The  physiological  cause  lies  in  the  capacity  of  short- 
leaf  pine  to  develop  on  the  upper  portion  of  the  root  and  lower  portion 
of  the  stem  special  reproductive  buds,  at  least  one  of  which  has  the 
same  function  as  the  central  terminal  bud  on  the  stem. 

The  double  crook,  at  the  upper  end  of  the  taproot  of  shortleaf  pine, 
characteristic  of  and  always  present  in  young  trees,  seems  to  be  inti- 
mately associated  with  its  power  of  reproduction  by  sprouts.  By 
means  of  this  double  crook  a  horizontal  section  from  1  to  3  inches  in 
length,  varying  with  the  age,  is  formed  at  the  upper  end  of  the  tap- 
root. This  form  persists  during  the  first  8  to  12  years,  after  which  its 
identity  becomes  lost  through  the  increasing  thickness  of  the  annual 
accretions.  It  is  significant  that  the  capacity  for  sprouting  is  coinci- 
dent with  the  period  during  which  the  root  maintains  this  character- 
istic form.  During  this  period  adventitious  stem  buds  are  present 
and  may  readily  be  seen  along  the  horizontal  section  of  the  root. 
The  corky  bark  here  is  unusually  thick,  affording  a  high  degree  of 
protection  against  ordinary  fires. 

The  killing  of  the  stem  is  followed  by  the  development  of  a  colony 
of  sprouts  at  the  base  of  the  stem  and  top  of  the  taproot,  usually  from 
6  to  1 2,  as  shown  in  figure  8,  and  not  infrequently  1 6  to  20.  Normally 
one  stem  (occasionally  two)  assumes  the  function  of  leader,  the  others 
being  more  or  less  procumbent  in  habit  and  serving  as  laterals  or 


LIFE    HISTORY   OF    SHORTLEAF    PINE. 


23 


Sprout'  feader- 


Fig.  8.— Sprout  shortleaf  pine  following  fire, showing  new  upright  stem,  secondary  sprouts,or  "laterals/ 
and  characteristic  crook  of  the  taproot.  Three-year-old  coppicefrom  7-year-old  seedling  parent.  (Drawn 
from  actual  specimen.) 


24 


BULLETIN    244,   U.    S.    DEPAETMENT   OF    AGRICULTURE. 


feeders.  In  the  organization  of  the  sprout  colony,  the  correlation  of 
the  two  classes  of  vegetative  buds  of  the  tree  is  thus  carried  out.  In 
producing  normally  a  single  new  upright  stem,  shortleaf  resembles 
the  hickories,  in  contrast  to  the  oaks  and  chestnut,  which  commonly 
mature  several  main  stems.  In  open  situations  and  miderstocked 
stands  a  tendency  to  develop  twin  stems  is  sometimes  seen  in  vigorous 
stands  of  shortleaf.  A  tendency  to  increase  the  number  of  stems 
above  two  appears  to  be  caused  directly  by  unfavorable  factors  of 
age,  weakness  of  the  parent,  poor  light  supply,  or  climatic  conditions. 
For  example,  as  many  as  42  coordinate  upright  stems  have  been 
counted  on  a  stump  4  inches  in  diameter,  cut  in  midsummer.  In 
coppice  stands  up  to  50  years  old,  a  few  twin  trees  will  usually  be 
found.  The  oldest  tree  of  undoubted  sprout  origin  observed  was 
226  years. 1 

Table  7. — Height  growth  of  doviinant  shortleaf  pine  in  pure,  well-stocked  stands  of  fire 
coppice  origin. ^ 


Age  (years). 

Height 
(feet). 

Age  (years). 

Height 

(feet). 

1.3 

10 

18.3 

9 

2.7 
4.2 
5.8 
7.5 
9.5 
11.6 
13.9 
16.1 

11.                       

20.6 

3 

12 

23.3 

26.0 

5 

14 

28.8 

6 

15 

31.7 

16 

34.7 

37.9 

9 

18 

41.0 

1  Based  on  100  individual  trees  and  the  average  trees  for  8  sample  plots  9  to  18  years. 

An  18-year-old  coppice  stand,  near  Glenville,  Nevada  County,  Ark., 
averaged  248  trees  per  acre.  Of  these,  71  trees  had  two  stems  each,  7 
had  three  steins,  and  1  had  four  stems,  or  a  total  of  336  stems  per  acre. 
Thus  33  per  cent  of  the  trees  had  more  than  one  stem.  The  sprout 
origin  of  the  stand  was  completely  identified,  but  there  is  no  record 
whether  the  cause  was  fire  or  chopping  to  clear  a  pasture.  The  stand 
was  vigorous  and  averaged  44  feet  high.  The  average  diameters  of 
all  stems  was  6.3  inches,  while  that  of  the  trees  proper,  or  each  tree 
colony  taken  as  a  unit,  was  7.4  inches.  Three  colonies  of  twin  trees 
and  some  single  stems  are  shown  in  Plate  V. 


1  A  large  twin-stemmed  tree  with  single  root  system  exposed  by  erosion  on  a  stream  bank.    There  were 
others  of  nearly  the  same  size  and  form  in  the  same  stand. 


LIFE    HISTORY   OF    SHORTLEAF    PINE. 


25 


Table  8. — Number  of  trees  per  acre  and  number  of  tree  stems  per  acre  in  18-year-old  coppice 
shortleaf  stand,  Nevada  County,  Ark. 


Diameter  breast  high  (inches). 

Trees  per  acre.' 

Total 

stems 

per 

acre. 

Stems  per  tree  colony. 

Total. 

1 

2 

3 

4 

2 

6 
28 
24 
9 
28 
27 
34 
6 
6 
1 

6 
29 
36 

47 
37 
39 
8 
6 
1 

6 

1 

8 
27 
18 
10 
5 
2 

30 

4                                            

3 
3 

1 

1 

53 

5 

72 

C7 

9 

1 

10 

1 

.       .   .  1 i 

Total 

1G9 

71  1             7  1             1 

248 

336 

'  Individual  trees  with  one  or  more  stems,  as  the  case  may  be. 

As  a  result  of  the  tree's  vigorous  coppicing  during  early  life,  short- 
leaf  occurs  characteristically  in  even-aged  stands.  A  fire  after  6  to 
8  years  reduces  to  a  single  age  class  all  the  several  ages  of  young 
growth  that  may  have  come  in  during  the  period.  This  has  been 
found  to  be  the  case  in  all  of  the  regions  studied.  It  is  significant 
in  this  connection  that  in  one  region  of  abundance  and  good  develop- 
ment of  shortleaf/  two  age  classes  strongly  predominated  throughout 
the  whole  stand.  One  group  consisted  of  pure  stands  from  160  to 
180  years  old  and  the  other  of  similarly  pure  stands  from  60  to  70 
years.  The  average  between  the  two  groups  is  105  years.  This  may 
be  looked  upon  as  indicating  the  occurrence  of  periods  of  either  tor- 
nadoes or  unusually  destructive  crown  fires.  The  60-year-old  age 
class  is  especially  abundant  over  the  region.  Old  local  records  may 
possibly  confirm  this  supposition  of  some  unusual  occurrence  of  the 
sort  indicated  between  the  years  1848  and  1852, 

SEASON    OF   YEAR. 

In  common  with  the  broadlcaf  species,  the  sprouting  takes  place 
least  actively  following  midsummer  cutting.  Pastures  and  rights 
of  way  are  thus  commonly  treated.  In  one  instance  a  pasture  con- 
tained a  good  stand  of  vigorous  shortleaf-pine  sprout  saplings,  4  years 
old  and  from  6  to  10  feet  high,  representing  the  third  generation  of 
coppice  from  winter  or  early  spring  cutting.  Along  railroad  rights 
of  way  in  the  Arkansas  region,  it  is  conmion  to  see  dense  sprout 
thickets  of  shortleaf  pine  due  to  repeated  mowing.  The  forest-fire 
season  occurs  during  the  fall  and  late  winter.  This  is  during  the 
period  of  vegetative  inactivity,  and  such  burnings  generally  result 
in  vigorous  sprout  growth  the  following  spring. 

1  Montgomery  and  Pike  Counties  In  western  central  Arkansas. 


fOREST  RESOURCES 

I  IRRARY 


26 


BULLETIN   244,   U.    S,   DEPARTMENT   OF   AGRICULTURE. 


METHOD   OF  DETERMINING   SPROUT   ORIGIN. 


Determination  of  the  sprout  origin  of  sliortleaf  pines  during  early- 
life  is  possible  by  means  of  external  characteristics.  The  presence  of 
a  colony  of  two  or  more  living  stems,  also  the  presence  of  dead  stems 
or  stubs  of  the  parent  tree  (charred  in  the  case  of  fire),  and  the  large 
size  of  the  sapling  or  pole  in  relation  to  its  age  are  clear  evidence  of 
coppice  origin.  A  clean,  smooth  base  without  scars  or  adjacent  stubs 
indicates  seedUng  origin.  This  evidence  is  sufhciont  and  dependable 
up  to  about  the  eighth  year.  Dead  stems  from  2  to  5  feet  high, 
when  killed  by  fire,  will  ordinarily  be  found  standing  at  the  end  of 
the  third  year.  In  very  early  life  sprout  stands  may  be  found  to 
contain  a  considerable  number  of  twin  and  triple  colonies,  but  the 
number  decreases  rapidly  with  advance  in  age.     In  the  latter  stands, 


Fig.  9.— Determination  of  origin  of  shortleaf  pine  by  basal  sections  at  the  ground:  A,  Tree  of  seedling 
origin;  B,  coppice  tree  64  years  old.  Diameter  of  core,  or  first  year's  growth,  is  3  times  and  cross-section 
area  8.9  times  that  of  tree  {A )  of  seedling  origin.    (From  photographs.) 

trees  are  frequently  seen  with  dead  or  dying  stems,  forked  at  an 
acute  angle  or  emerging  from  their  sides,  at  distances  a  few  feet 
above  the  ground.  Following  the  first  6  to  10  years  no  external 
characteristics  are  usually  apparent  except  occasionally  multiple 
living  stems. 

The  first  year's  stem  growth  of  trees  of  seedling  origm  is  about  as 
thick  as  a  darning  needle  and  2  to  4  inches  high,  while  the  corresponding 
growth  of  young  coppice  sprouts  is  commonly  as  large  as  an  ordinary 
lead  pencil  in  diameter  and  about  double  its  length.  (Fig.  9.)  The 
following  few  years'  growth  in  each  case  is  on  a  proportional  scale. 
Thus  the  character  of  early  growth,  particularly  that  of  the  first  year, 
recorded  in  the  base  of  the  tree  and  visible  when  the  tree  is  cut  level 
with  the  ground,  affords  a  dependable  record  of  the  origin  of  the  tree. 
Coppice  trees,  furthermore,  usually  have  some  of  the  dead  stubs  of 


LIFE   HISTORY   OF    SHORTLEAF   PINE. 


27 


the  former  generation  embedded  at  their  bases.  (Fig,  10.)  In  most 
cases  fire  has  been  the  cause  of  the  sprouting,  and  since  both  the  inclu- 
sion of  charred  stubs  and  the  size  of  the  core  can  readily  be  ascer- 


Lateral  root 


Taproot 


Fig.  10.— Vertical  section  through  base  of  18-year-old,  thrifty  shortleaf  pine  of  coppice  origin,  inclosing  stub 
of  parent  stem.    (From  photograph.) 

tained,  if  present,  by  an  examination  of  the  extreme  base  of  the  tree, 
these  marks  embedded  similarly  in  a  number  of  trees  selected  at 
random  will  serve  to  confirm  the  coppice  origin  of  the  whole  stand. 
An  indication  of  origin  may  be  seen  in  low-cut  stumps  ^  in  logging 

1  In  Arkansas  6  to  9  Inches  high  for  small  trees  and  1  foot  for  the  larger  ones  are  customfffy  heights. 


28 


BULLETIN   244,   U.    S.    DEPARTMENT   OF   AGRICULTURE. 


areas,  tlie  core  of  coppice  being  composed  of  large  conspicuous  rings 
in  contrast  to  the  small  rings  of  seedling  trees. 

ECONOMIC   VALUE. 

Fire  as  a  menace  to  young  pine  in  great  measure  prevents  capital 
from  going  into  what  otherwise  appears  to  be  a  paying  investment. 
Wliite  pme  in  New  England  is  a  well-known  example.  The  case  is 
somewhat  different  with  shortleaf,  in  which  practically  the  only  fire 
loss  is  from  exceptionally  hot  fires  which  destroy  large  sapUngs  or 
pole  stands  too  large  to  sprout.  Repeated  burning  in  the  dormant 
seasons  of  the  year,  when  almost  all  fires  occur,  seems  to  offer  no 
appreciable  setback  for  at  least  three  sprout  generations.  Therefore 
the  element  of  fire  risk  in  the  production  of  all  important  eastern 
coniferous  species  is  reduced  to  the  minimum  in  shortleaf  pine  by 
its  vigorous  sprouting  habit.  This  feature  highly  recommends  the 
species  for  profitable  managment  throughout  its  range. 

GROWTH. 


The  long  growing  season  throughout  most  of  its  range  and  its 
inherent  vigor  make  shortleaf  pine  a  tree  of  rapid  height  growth. 
In  situations  of  equal  favorableness  it  is  more  rapid  than  longleaf 
pine  and  only  slightly  less  so  than  loblolly  pine.  On  average  upland 
soils  typical  of  most  of  its  range  it  excels  its  most  common  associates 
among  the  oaks  and  hickories.  In  Arkansas  and  adjacent  States,  on 
the  better  sites  bigbud  and  bitternut  hickories  are  distinctly  below  it, 
yellow  and  Spanish  oaks  nearly  equal  it,  and  sweet  gum  slightly 
exceeds  it  m  height  growth.  In  the  Piedmont  and  Arkansas  regions 
height  growth  is  not  widely  different  on  similar  qualities  of  site. 
Table  9  shows  the  rate  of  growth  and  relation  of  heights  to  age  for 
the  two  reo;ions.^ 


Table    9. — Height  growth   of  shortleaf  pine,    based  on 

Carolina.'^ 


in   Arkansas   and  North 


V.^ESTERN 

ARKANSAS. 

Age  (years). 

Height. 

Age  (years). 

Height. 

Maximum. 

Average. 

Minimum. 

Maximum. 

Average. 

Minimum. 

20 

Feet. 
51 
56 
59 
62 
64 
66 
68 
69 
71 
72 
74 
75 
76 
78 

Feet. 
45 
50 
64 
57 
60 
62 
64 
65 
66 
67 
69 
70 
71 
72 

Feet. 

37 
43 
48 
52 
54 
57 
59 
60 
62 
63 
64 
65 
65 
66 

90 

Feet. 
79 
80 
81 
83 
85 
87 

.89 
90 
91 
92 
93 
93 

Feet. 
73 
74 
74 
76 
77 
78 
79 
80 
81 
81 

82 
83 

Feet. 

67 

25 

95            

30 

100 

68 

110 

70 

45 

130 

71 

50 

140 

71 

55 

150 

71 

60 

160 

72 

170 

72 

70 

ISO 

72 

75 

190 

72 

80 

200 

73 

85 

1  Table  7  shows  the  height  growth  of  shortleaf  known  to  be  of  coppice  origin. 

2  The  Arkansas  table  is  based  on  age-height  measurements  of  285  trees  and  diameter-height  of  3,214 
trees;  the  North  Carolina  table  is  based  on  age-height  measurements  of  332  trees  and  diameter-height  of  384 
trees. 


LIFE    HISTORY   OF    SHORTLEAF    PINE. 


29 


Table  9. — Height  growth  of  shortleaf  jrine,  based  on   age,  in  ArJcansas  and  North 
Carolina — -Continued . 

PIEDMONT  REGION,  NORTH  CAROLINA. 


Age  (years). 

Height. 

Age  (years). 

Height. 

Maximum. 

Average.      Minimum. 

Maximum. 

Average. 

Minimum. 

5 

Feet. 
22 
4S 
63 
69 
71 
73 
74 
75 

Feet.' 
13 
29 
42 
50 
57 
61 
63 
65 

Feet. 

45 

Icet. 
75 
76 
76 

i 

Feet. 
67 
68 
69 

70 
70 
70 
71 

Feet. 

40 

10 

ih 

15 
20 
25 
29 
33 
36 

50 

55 

43 

45 

20 

60 

4S 

25 

65 

49 

30 

70 

80 

40 

55 

During  early  life  the  terminal  leader  of  shortleaf  pine  commonly 
forms  from  two  to  four  secondary  or  false  terminal  nodes  during  the 
growing  season.  These  are  accompanied  by  false  rings  of  growth  in 
the  wood,  usually  plainly  marked  and  apt  to  be  mistaken  for  true 
rings. 

The  influence  of  side  light  upon  height  growth  is  well  illustrated  in 
figure  5,  showing  a  10-year-old  stand  of  shortleaf  with  the  east  and 
west  side  light  cut  ofi'  by  an  adjacent  stand.  The  heights  increase 
from  2  feet  near  the  margin  to  22  feet  under  full  hght.  This  illus- 
trates very  well  the  need  of  light  for  development,  and,  at  the  same 
time,  the  power  of  endurance  of  shortleaf  under  limited  light  supply. 
A  9-year-old  stand  with  3,800  trees  per  acre  averaged  19  feet  high 
as  compared  with  only  16  feet  for  a  near-by  stand  of  the  same  age 
and  on  similar  soil  with  12,200  trees  per  acre.  Two  adjacent  young 
stands,  similar  in  all  points  except  tree  density,  averaged  9  feet  high 
for  4,100  trees  per  acre  and  5  feet  high  for  32,000  trees  per  acre. 


DIAMETER. 


The  rate  of  diameter  growth  of  shortleaf  pine  is  intermediate  be- 
tween that  of  loblolly  and  that  of  longleaf  pine,  the  slowest  of  the 
important  southern  pines.  Besides  the  well-defined  annual  rings  of 
wood  which  clearly  record  diameter  growth,  from  two  to  four  ter- 
minal nodes  in  the  stem  of  the  tree,  accompanied  by  shght  resting 
periods  in  the  tree's  activity,  usually  occur  during  the  period  of 
vigorous  growth  in  earlier  Ufe.  These  growth  periods  are  recorded  by 
fine  lines  of  denser  wood  within  the  true  annual  rings.  Periods  of 
injury,  caused  by  insect  attack,  fire,  or  severe  drought  during  which 
growth  is  temporarily  checked,  usually  have  the  same  effect.  Such 
fines,  forming  false  rings,  are  freciuent  in  shortleaf  pine,  and  must  be 
distinguished  in  examining  a  cross  section  for  age.  Prominent  bands 
of  wood  stained  brown  in  color  are  particularly  apt  to  be  found  in 


30 


BULLETIN   244,   U.    S.    DEPARTMENT  OF   AGRICULTURE. 


young  shortleaf  and  erroneously  mistaken  for  true  annual  rings  of 
growth. 

Diameters  throughout  this  bulletin,  unless  otherwise  stated,  are 
measured  at  breast  height  (4^  feet  above  the  ground).  Table  10 
shows  the  diameter  growth  based  on  age  for  the  Piedmont  region  of 
North  Carolina  and  for  western  Arkansas.  The  tables  may  be  con- 
sidered as  broadly  applicable  to  large  areas  within  the  two  specified 
regions,  since  differences  in  growth  over  large  areas  are  not  important 
except  as  caused  by  local  variation  in  quality  of  situation. 

Table  10. — Diameter  growth  of  shortleaf  pine,  on  the  basis  of  age,  in  Arkansas  and  North 

Carolina.^ 


WESTERN   ARKANSAS. 


Age  (years). 

Diameter  breast  high. 

Age  (years). 

Diameter  breast  high. 

Maximum. 

Average. 

Minimum. 

Maximum. 

Average. 

Mmimum. 

Inches. 
7.2 
8.6 
9.9 
11.0 
12.0 
12.8 
13.6 
14.4 
15.1 
15.7 
16.3 
16.9 
17.5 
18.0 

Inches. 
5.7 
7.0 
8.1 
9.1 
10.1 
10.9 
11.7 
12.3 
12.9 
1.3.5 
14.0 
14.5 
15.0 
15.5 

Inches. 
4.3 
5.4 
6.4 
7.4 
8.2 
9.0 
9.7 
10.3 
10.8 
11.3 
11.8 
12.2 
12.6 
12.9 

90 

Inches: 
IS.  5 
19.0 
19.4 
20.3 
21.1 
21.7 
22.3 
22.8 
23.2 
23.6 
23.9 
24.1 
24.3 

Inches. 
15.9 
16.3 
16.6 
17.3 
17.8 
18.3 
18.7 
19.0 
19.3 
19.6 
19.7 
19.9 
20.1 

Inches. 

95 

95. 

13.6 

30 

100 

13.8 

110 

14.2 

40 

120 

14.6 

130 

14.9 

50 

140 

15.1 

55 

150 

15.  3 

60 

160 

15.4 

65 

170 

15.5 

70 

180 

15.  6 

190 

15.7 

80 

200 

15.8 

85 

PIEDMONT   REGION,   NORTH  CAROLINA. 


2.0 
5.9 
9.2 
11.6 
13.3 
14.5 
15.6 
16.5 


45, 
50, 
55, 
60 
65 
70 
75, 
80 


17.1 

10.5 

17.  6 

11.0 

18.0 

11.4 

18.4 

11.7 

18.7 

12.1 

19.0 

12.4 

19.2 

19.4 

13.0 

4.5 
5.0 
5.4 
5.8 
6.1 
6.4 


1  The  table  for  Arkansas  is  based  on  breast-high  diameter  measxu-ements  of  285  trees  and  34  trees  repre- 
senting the  average  of  even-aged  plots;  the  North  Carolina  table  is  based  on  decade  measurements  on  332 
stumps,  26  to  89  years  old. 

The  close  relation  between  tree  density  and  growth  in  diameter  is 
illustrated  in  Table  11,  compiled  from  measurements  on  unit  areas 
of  different  density  of  trees  of  a  30-year-old  fully  stocked  shortleaf 
stand.  In  seven  consecutive  sample  areas  of  one-tenth  acre  each, 
the  size  of  the  diameter  class  prevailing  on  each  plot  increased  regu- 
larly with  a  corresponding  regular  decrease  in  the  number  of  trees 
per  acre.  So  far  as  is  known  this  close  relation  holds  true  for  all 
pure  stands  of  shortleaf  pine. 


LIFE    HISTORY   OF    SHORTLEAF   PIXE. 


31 


Table  11. — Relation  of  tree  density  and  diameter  grov.th  in  30-year-old  pure  stands  of 
shortleaf  of  varying  densities,  Arkansas  National  Forest} 


Prevailing  diameter  class 
(inches).2 

Tree  den- 
sity (trees 
per  acre). 

Decrease 

(trees  per 

acre). 

Prevailing  diameter  class 
(inches).^ 

Tree  den- 
sity (trees 
per  acre). 

Decrease 

(trees  per 
acre;. 

4 

800 
720 
640 
560 

8 

475 
390 
300 
210 

85 

80 
80 
80 

10 

7                 .               ... 

1  11 

90 

»  Based  on  seven  plots  in  the  same  stand  of  varying  density,  but  having  uniform  soil  conditions. 
*  The  diameter  class  having  the  largest  number  of  trees  in  the  individual  stand. 

VOLUME    GROWTH. 

The  merchantable  contents  of  a  tree  obviously  depends  upon  total 
height  and  diameter  taken  at  successive  points  along  the  stem.  The 
rise  in  percentage  of  the  rate  of  increase  in  the  volume  of  shortleaf 
pine  in  common  with  most  trees  culminates  at  a  comparatively  early 
age,  considerably  prior  to  the  year  of  maximum  production  of  wood 
for  the  individual  tree.  Furthermore,  the  highest  annual  production 
of  wood  is  reached  somewhat  earlier  than  the  production  of  saw 
timber.  In  stands  of  relatively  ecjual  density  those  on  the  poorer 
sites  and  near  the  margin  of  natural  distribution  reach  the  maximum 
rate  of  volume  production  at  a  later  age  than  similar  stands  on 
more  favorable  sites  and  more  centrally  situated  within  the  region  of 
distribution.  For  example,  the  individual  trees  in  stands  in  Missouri, 
West  Virginia,  and  New  Jersey  apparently  show  the  gi'eatest  annual 
wood  increment  at  about  70  years,  but  in  North  Carolina  the  culmi- 
nation is  reached  at  about  50  years,  and  in  Arkansas  at  about  35 
to  40  years.^  The  contents  in  board  feet  and  cubic  feet  of  trees  of 
different  ages,  up  to  80  years,  for  two  qualities  of  site,  are  shown  in 
Table  12. 

Table  12. —  Volume  of  shortleaf  pine  in  North  Carolina,  hosed  on  age  for  two  site  classes. 


[Based  on  diameter  growth  of  332  trees,  and  volume  table.    Stump  height 
1.5  feet  for  trees  17  inches  and  over.] 

,  1  loot  for  trees  6  to  16  inches; 

Saw  timber. 

Solid  contents.  2 

Age  (years). 

Scribner  rule. 

Doyle  rule. 

Quality 

Quality 

Quality 

Quality 

Quality 

Qu^ality 

15 

Boardfeet. 
51 
100 
147 
186 
221 
251 
275 
2% 
315 
331 
345 
357 
369 
381 

Boardfeet. 

Boardfeet. 

50 
87 
125 
160 
191 
216 
237 
255 
271 
284 
295 
306 
316 

Boardfeet. 

Cubic  feet. 
13.5 
24 
34 
43 
50 
56 
61 
65 
69 
72 
75 
78 
80 
82 

Cuhicfeet. 

20 

6 
23 
38 
51 
63 
75 
86 
96 
105 
113 
121 
129 
135 

3 

11 
17 
24 
32 
39 
46 
53 
60 
66 
73 
79 

2.6 
6.7 
10.3 
13.8 
16.7 
19.3 
22.0 
24.0 
26.0 
28.0 
29.0 
31.0 
32.0 

25 

30. . . . 

35 

40 

45 

50 

55. 

60 

65 

70.... 

75 

80 

»  For  volume  tables  of  shortleaf  pine  based  upon  height  and  logs  per  tree,  see  a  forthcoming  bulletin  on 
the  Importance  and  management  of  shortleaf  pine. 
*  Total  volume  of  stem,  including  bark,  between  stump  and  top  diameter,  outside  bark,  of  5.5  inches. 


32  BULLETIN   244,   U.    S.   DEPARTMENT   OF   AGRICULTURE. 

RECOVERY   AFTER   SUPPRESSION. 

Shortleaf  pine  possesses  to  a  high  degree  the  abihty  to  recover  after 
suppression.  This  feature  is  well  exhibited  in  a  rapid  increase  in 
diameter  growth  following  an  increase  in  the  supply  of  light.  Events 
of  any  sort  which  produce  changes  in  stand  densities  are  recorded 
in  quite  a  remarkable  manner  by  shortleaf  pine. 

8 


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Fig.  11.— Effect  of  an  ice  storm  upon  subsequent  diameter  growth  in  a  22-year-oId  crowded  shortleaf  stand. 
Tree  1,  formerly  dominant,  permanently  bent  over  by  ice  and  suppressed  for  a  period  of  14  years:  tree 
2,  formerly  partially  suppressed,  given  more  light  by  the  storm,  vigorous  and  dominant  for  the  past  14 
years. 

The  effect  of  a  heavy  ice  storm  upon  a  thrifty  22-year-old  fully 
stocked  stand  in  Nevada  County,  Ark.,  as  recorded  by  the  diameter 
growth,  is  seen  in  figure  1 1  and  Plate  VIII.  The  storm  occurred  in 
December,  1898,  and  the  stand  in  1912  was  36  years  old.  The  heavy 
ice  bent  over  many  of  the  larger-crowned,  dominant  trees,  thereby 
opening  up  many  smaller-crowned,   middle  and  lower  class   trees. 


3ul,  244,  U.  S.  Dept.  of  Agricuitu 


Plate  V. 


ill  244,  U.  S.  Dept.  of  Agricultui 


Section  Through  Base  of  65-Year-Old  Twin  Shortleaf  Pine  of  Sprout  Origin. 


.  244    U,  S.  Dept.  of  Agriculture. 


Plate  VII. 


/ 
Diameter  l4-inches,30 
years  after  thinning 
467 percent  increase 
in  cross-section. 
Aqe.68  years. 


at  time  oftlninping- 
by  cyclone.ataqe  of 


Rapid  Recovery  of  Shortleaf  Pine  after  Suppression.  Effect  of  Natural 
Thinning  by  Tornado,  31  Years  Ago,  upon  Tree  58  Years  Old.  Arkansas 
National  Forest. 


244,  U.  S.  Dept.  of  Agriculture 


244,  U.  S.  Dept.  of  Agriculture 


Plate  IX. 


Fig.  1.— Effect  OF   Nantucket  Tip  Moth   (Lefti  on  8-Year-Old  Coppice  Short- 
leaf.    Trees  Same  Age  and  Height  at  Opening  of  Season. 


Fig.  2.— Effect  of  Ice  St_=,-.:  a,^t  =  r  a  L-pse  of  14  Years. 
INJURY     BY    INSECTS    AND    HEAVY    STORMS. 


3ul.  244,  U.  S.  Dept.  of  Agriculture. 


^v./!^ 


^sf  t- 


'3^. 


^f^'^''^^'^^^^ 
'^^  = 


LIFE   HISTOBY  OF   SHORTLEAF   PINE. 


33 


The  storm  lasted  for  nearly  a  week  and  many  of  the  bent  trees  which 
were  given  a  permanent  "set"  were  alive  after  14  years  of  suppres- 
sion. The  record  of  interchange  of  crown  classification  and  resultant 
growth  is  well  illustrated  in  the  breast-high  sections  of  two  repre- 
sentative trees  shown  in  the  illustration.  In  the  10-year  period  fol- 
lowing the  storm,  the  tree  suppressed  ])y  the  ice  changed  from  97  per 
cent  to  13  per  cent  rate  of  diameter  growth,  while  an  adjacent  and 
formerly  partly  suppressed  tree  showed,  as  a  result  of  the  opening  up, 
an  increase  of  growth  from  65  to  122  per  cent. 

An  immediate  response  in  diameter  growth  at  the  age  of  58  years 
is  exhibited  in  Plate  VII,  showing  a  representative  tree  opened  up  .31 
years  prior  by  a  tornado  in  Montgomery  County,  Ark.  As  a  result 
of  this  natural  thinning  the  growth  averaged  8  rings  to  the  inch  for 
the  30  years  following  as  compared  with  16  rings  per  inch  for  the  30 
years  preceding  the  natural  thinning.     The  increase  in  basal  area 


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Fig.  12.— Increased  rate  of  growth  of  7  representative  shortleaf  pine  trees  on  a  typical  cut^over  tract,  cut 
5  years  ago.    Growth  in  basal  area  at  breast  height,  for  successive  .5-year  periods,  during  the  past  30  years. 

was  487  per  cent  during  the  latter  period.  The  immediate  recovery 
is  shown  by  the  increase  during  the  first  season.  The  tornado  made 
a  clean  sweep  along  the  center,  about  one-haK  mile  in  width,  and  a 
thinning  of  decreasing  degree  toward  the  margin  of  its  path,  which 
was  about  14  miles  in  length. 

The  abiUty  of  a  species  to  recover  from  suppression  can  be  ascer- 
tained by  a  study  of  cut-over  areas  following  logging  operations. 
The  stimulation  in  growth  of  shortleaf  pine  on  a  typical  cut-over  tract, 
logged  to  an  approximate  minimum  stump  diameter  of  14  inches^  5 
years  prior  to  the  examination,  is  shown  graphically  in  figure  12,  based 
on  Table  13.  The  increase  in  basal  area  during  the  five  years  following 
logging  is  contrasted  with  the  increases  for  the  five  preceding  five-year 
periods.  Practically  all  trees  observed  showed  stimulated  growth  due 
to  thinning  and  increased  light  supply.  Trees  formerly  suppressed, 
however,  grew  relatively  much  faster  after  the  logging.     The  least  gain 


Hellbig,  Ark.,  near  the  Arkansas  National  Forest,  logged  in  1907  and  examined  in  1912. 


34 


BULLETIN   244,   U.    S.    DEPARTMENT   OF   AORICULTUEE. 


ill  basal  area  at  breast  height  was  75.4  per  cent,  the  largest  311  per 
cent,  and  the  average  for  7  representative  trees  was  171.4  per  cent 
over  their  former  rates  of  growth.  The  trees  ranged  from  45  to  101 
years  old  at  the  time  of  the  logging,  but  most  of  them  were  between 
60  and  70  years.  Since  height  growth  was  mainly  complete  at  this 
age,  it  is  perfectly  safe  to  say  that  the  volume  increment  of  the  trees 
took  place  at  approximately  the  same  or  possibly  at  a  somewhat 
greater  rate,  because  of  the  greater  increase  in  the  size  of  the  upper 
part  of  the  stem  at  this  age. 

Table  13. — Comparative  growth  of  shortleafin  Jive-year  periods  before  and  after  logging. ' 


Age  at 
time  of 
logging. 

Increase  in  basal  area  (breast  height). 

Five-year  periods  prior  to  logging. 

Five- 
year 
period 
after 
logging. 
190,8-1912. 

Rate  of 

Tree  No. 

188.3-18S7 

188,S-1892 

189,3-1897 

1898-1902 

1903-1907 

since 
logging 
over  pre- 
vious 
five-year 
periods. 

45 
57 
65 
65 
69 
69 
101 

Sq.  in. 
4.2 
2.0 
4.6 
1.7 
4.5 
3.2 
5.S 

Sq.  in. 
4.9 
6.2 
7.2 
3.6 
9.5 
10.1 
6.0 

Sq.  in. 
5.6 

13.0 
7.8 
3.9 

10.5 
8.2 
6.3 

Sq.  in. 
6.5 
8.1 
5.6 
6.3 
8.6 
11.8 
6.5 

Sq.  in. 
8.2 
6.8 
8.8 
6.9 
6.0 
12.8 
6.8 

Sq.  in. 
14.4 
12.4 
15.8 
24.0 
16.1 
52.7 
18.0 

Percent. 
15.  i 

2 

83.0 

3 

80.3 

247.9 

5 

6 

166.6 
311.2 

165.9 

Average 

67 

3.7 

6.8 

..9|           7.« 

8.0 

21.9 

171.4 

1  Typical  shortleaf  stand  cut  5  years  ago  to  an  approximate  diameter  limit  of  14  inches  in  average  quality 
site  in  western  Arkansas. 

CAUSES   OF   INJURY. 


The  damage  to  forest  growth  caused  by  fire  far  exceeds  the  com- 
bined effect  of  all  other  injurious  agencies.  At  the  same  time,  this 
cause  of  injury  is  the  most  susceptible  to  control  of  man.  The  annual 
burning  of  the  forest  floor,  extensively  practiced  in  the  past  through- 
out the  shortleaf  region,  has  been  done  with  little  realization  of  the 
damage  to  the  forest.  Shortleaf  which  has  passed  the  earlier  stages 
suffers  much  pennanent  injury  from  fire.  Abundant  seeding,  low  resin 
content  of  the  wood,  and  early  rapid  height  growth,  in  addition  to 
sprouting,  afford  shortleaf  perhaps  the  best  chance  of  any  of  the  im- 
portant southern  pines  to  survive  under  adverse  conditions  caused  by 
fire,  but  in  spite  of  these  favorable  characteristics  much  loss  and  injury 


Completely  stocked  stands  of  shortleaf  over  20  years  in  age  are 
rarely  found  m  tracts  of  considerable  size,  except  in  old  fields  and  in 
other  situations  where  fire  has  been  practically  excluded.  As  a  rule, 
the  stand  is  irregular  m  density,  with  many  small  openings,  for  which 


LIFE   HISTORY   OF   SHOETLEAF   PIXE.  35 

fire  is  chiefly  responsible.  The  heaviest  direct  mjuiy  to  the  stand 
occurs  just  after  the  ages  of  8  to  12  years,  because  prior  to  this  time 
the  young  forest  is  quickly  restored  by  its  power  of  coppicing. 
Repeated  burnings,  however,  cause  a  setback  which  the  tree  is  able  to 
make  up  only  in  part.  In  older  trees  the  effect  of  frequent  fires  is 
cumulative  in  weakening  the  tree  at  its  base,  resulting  in  its  over- 
tlirow  during  high  wind.  Although  not  so  complete  in  the  case  of 
shortleaf  as  in  that  of  the  more  resinous  longleaf ,  the  sort  of  decima- 
tion of  stands  is  continuous  and  rapid  where  fire  occurs  frequently. 
External  injury  and  loss  in  vitahty,  due  to  excessive  heat,  open  up 
avenues  of  ready  attack  by  insects  and  fungi. 

Ordinary  surface  fires  usually  develop  sufficient  heat  to  kill  back 
trees  up  to  6  or  8  feet  in  height,  and  to  injure  trees  from  about  7  to  12 
feet  in  height.  Basal  fire  scars  heal  rapidly,  and  during  intei-vals 
])etween  fires  thrifty  pole  and  standard  trees  usually  succeed  in  com- 
pletely covering  them.  Such  cases  are  quite  frequently  noted  in  ex- 
amining the  tops  of  stumps.  The  damage  and  loss  due  to  fire  is  mainly 
m  the  form  of  defective  lumber  and  reduced  yield  per  acre  from  the 
stand,  which  may  be  ascertained  by  measuring  the  yields  from  well- 
stocked  groups  selected  within  a  stand  and  comparing  them  with  its 
total  yield.  The  wide  difference  between  the  two  is  perhaps  the  most 
impressive  measure  of  the  beneficial  effect  of  protection,  since  fire  can 
safely  be  considered  one  of  the  most  active  causes  of  the  poorly 
stocked  condition  of  our  forest  stands. 

INSECTS  1    AND   MAMMALS. 

Of  aU  insects,  the  southern  pine  beetle  (Dendroctonus  frontalis 
Zimm.)  is  undoubtedly  the  most  injurious  to  shortleaf  pine.  It  is 
active  throughout  the  warmer  portions  of  the  year,  passing  through 
the  bark  to  the  cambium,  or  living  layer,  and  there  eating  out  long, 
winding  furrows  or  egg  galleries,  which  partially  girdle  and  weaken  the 
tree.  The  eggs  hatch  into  grubs,  which  feed  on  this  tissue,  completing 
the  girdling  and  destroying  the  tree.  Serious  invasions  of  this  insect 
occurred  in  1890,  1893,  and  1910.  The  last  outbreak  led  to  a  special 
study  by  the  Bureau  of  Entomology,  whose  report,^  describing  fully 
its  life  history  and  giving  recommendations  for  controUing  the  insect 
pest,  may  be  obtained  upon  application  to  the  Division  of  PubMca- 
tions,  Department  of  Agriculture,  Washington,  D.  C.  It  has  been 
demonstrated  that  using  trees  that  die  in  the  fall  and  early  winter  for 
fuel  or  other  purposes  durmg  the  winter  serves  both  to  control  the 
beetle  and  to  prevent  its  outbreak.  This  is  an  important  point  to 
bear  in  mind  in  handling  shortleaf  stands. 

1  For  further  information  in  regard  to  causes  of  injury  by  insects,  apply  to  the  OflSce  of  Insect  Investiga- 
tions, Bureau  of  Entomologj-,  U.  S.  Department  of  Agriculture. 

2  Farmers'  Bulletin  476,  "The  Dying  of  Pine  in  the  Southern  States:  Cause,  Extent,  and  Remedy," 
U.  S.  Department  of  Agriculture.  Also,  Bureau  of  Entomology  Bulletin  83,  Part  I,  "Bark  Beetles  of  the 
Genus  Dendroctonus,"  by  Dr.  A.  D.  Hopkins,  p.  56. 


36  BULLETIN   244,   U.    S.   DEPARTMENT   OF   AGRICULTURE. 

The  Nantucket  pine-tip  moth  {Eetinia  frustrana  Scud.)  attacks 
and  deforms  the  rapid-growing  tips  of  branches.  The  attack  of  this 
insect  is  locally  the  most  perceptible  injury,  but  the  insect  is  not  a 
serious  menace.  The  presence  of  dead  tips  and  pitch  exudations  are 
the  characteristic  external  signs  of  the  attack,  usually  equally  present 
on  other  pines,  for  the  insect  is  widely  distributed  and  attacks  ^vdthout 
apparent  discrimination  practically  all  pmes.  As  a  rule,  the  msect 
is  not  abundant  for  more  than  one  or  possibly  two  years.  By  virtue 
of  its  high  vigor  and  its  capacity  for  forming  new  shoots,  shortleaf 
pine  recovers  rapidly  after  an  attack,  suffering  mainly  the  loss  of 
time  during  the  period  of  arrested  growth. 

Trees  cut  or  thrown  durmg  the  summer  months  soon  become  m- 
fested  with  larvae  of  the  southern  pine  sawyer,  or  borer,  known  com- 
monly as  a  ^'flathead."  ^  The  larvae  of  this  genus,  Monoliammus,^ 
hatched  from  eggs  laid  under  the  bark,  feed  on  the  rich  sapwood,  but 
seldom  penetrate  to  the  heartwood.  They  never  attack  living  trees 
in  the  South.  Rapid  dryuig  of  the  logs  is  the  surest  prevention;  so 
that  trees  cut  in  the  summer  months  should  be  removed  from  stands 
to  dry  situations  exposed  to  sun  and  wind,  or  barked  and  opened  up 
fully.     Immersion  in  water  where  possible  is  the  simplest  remedy. 

Mice,  chipmunks,  squirrels,  and  birds  are  very  destructive  of  seed, 
and,  to  some  degree,  of  seedhngs.  The  abundant  production  of  seed, 
however,  accounts  for  the  plentiful  regeneration  of  shortleaf  m  spite 
of  these  enemies.  On  account  of  the  small  size  of  the  seed,  hogs 
destroy  little  or  none  directly,  and  they  cover  many  in  the  process  of 
rooting,  so  that  the  hog  is  to  be  looked  upon  rather  as  a  benefit  than 
a  menace  to  the  shortleaf  forest.  In  mixed  pine  and  nut-bearing 
forests,  the  presence  of  the  hog  is  decidedly  favorable  to  the  regen- 
eration of  pme  through  the  destruction  of  the  hardwood  seeds.  In 
artificial  forestation,  mammals  and  birds  are  always  one  of  the  chief 
sources  of  injury,  because  they  destroy  large  quantities  of  seed. 

FUNGI. 

The  southern  timber  pines  as  a  group  are  not  badly  infested  with 
timber-destrojdng  fungi  until  advanced  in  age  or  weU  past  maturity. 
Up  to  100  years  of  age,  shortleaf  pine  is  remarkably  low  in  suscepti- 
bility to  fungus  attack;  above  this  age,  and  especially  after  the  age  of 
about  150  years,  in  regions  subject  to  frequent  fires,  fungi  are  more 
prolific  and  more  easily  gain  a  foothold  in  the  tree. 

Three  species  of  fungi  are  more  or  less  common  in  shortleaf  pine 
and  cause  nearly,  all  of  the  wood  rot  commonly  known  as  '  'redheart."  '' 
Two  species  of  fungi,  Polyporus  schweimtzii  and  Polyporus  sul- 
phureus,  enter  the  tree  through  wounds  on  the  butt  or  on  the  stool  of 

1  The  insect  is  really  a  roundheaded  borer,  and  not  a  member  of  the  flat-headed  group. 

2  Chiefly,  Monohammus  tililator  Fab.  See  Bureau  of  Entomology  Bulletin  58,  "Some  Insects  Injurious 
to  Forests,"  p.  41. 

3  Long,  W.  H.,  Office  of  Forest  Pathology,  U.  S.  Department  of  Agriculture. 


LIFE    HISTORY   OF    SHORTLEAF   PINE. 


37 


the  tree  just  below  the  surface  of  the  ground,  causing  butt  rot;  and 
one  enters  through  branch  stubS;  knot  holes,  or  other  openings 
through  the  living  sapwood  in  the  upper  portion  of  the  tree,  pro- 
(Kicing  the  true  redheart.  This  disease  is  probably  the  most  usual 
and  is  caused  by  Trametes  fini.  It  travels  downward  and  sometimes 
reaches  to  the  base  of  the  tree,  leaving  the  wood  firm  rather  than  pow- 
dery, of  a  rich  or  dark  reddish  color,  and  permeated  by  oval  or  lens- 
shaped  pockets  of  a  light-gray  color.  The  well-known  dark-colored 
"punks,"  or  fruiting  bodies,  are  almost  invariably  from  this  species, 
since  the  other  two  common  fungi  have  annual  fruiting  bodies. 

The  Polyporus  scliiveinitzii  leaves  the  wood  in  characteristic  brown- 
colored  cubical  blocks.  The  fruiting  bodies  are  hairy  on  top,  brown 
inside,  and  weather  brown.  They  are  short-lived  and  are  seldom 
seen.  The  sporophore  or  "punk"  of  Polyporus  sulphureus  is  yellow 
on  the  outside  changing  to  white,  and  its  contents  is  white.  Its 
work  may  be  known  by  characteristic  white  bands  of  mycelium, 
which  radiate  outward  from  the  center  of  the  tree,  filling  the  cracks 
in  the  rotted  wood  with  felt-like  masses  of  fungous  tissue. 

In  cutting  stands  up  to  70  years  old  heart  rot  is  found  infrequently. 
The  liability  to  infection  increases  with  the  declining  vitality  of  the 
tree.  In  one  representative  even-aged  forest  stand,  60  to  65,  years  in 
central  Arkansas,  only  2.2  per  cent  of  the  logs  showed  injury  by  fungi. 
In  four  large  even-aged  groups  of  shortleaf  pine,  170  years  old,  the 
diseased  logs  ranged  from  20  to  27  per  cent  of  the  total  number  of  logs 
utilized,  or  17.4  per  cent  of  aU  logs,  including  sound  logs  left  in  the 
tops,  which  are  merchantable  or  will  be  soon.  A  record  of  the  in- 
fected logs  in  virgin  timber  at  a  large  sawmill  in  Pike  County,  Ark., 
for  March,  April,  and  May,  1912,  shov/ed  25,689  sound  logs  and  4,430, 
or  14.7  per  cent  of  the  total  logs,  unsound.  The  log  scale  was  slightly 
more  than  3^  million  board  feet.  The  average  run  of  infected  timber 
for  central  Arkansas  is  further  indicated  in  Table  14. 

Table  14. — Amount  of  "redheart"  infection  in  average  forest  run  shortleaf  pine,  mostly 
60  to  180  years  old.^ 


Total  cut 
for 


Redheart 
defect. 


Percentage 
sound. 


Percentage 
infected 

with 
redheart. 


Jime 

July 

August 

September. 

October 

November. 
December.. 


January. . 
FebruaVy. 

March 

April 

May 


Board  feet. 
1,907,461 
1,741,235 
1,597,014 
1,862,025 
1, 185, 132 
1,087,018 
1,008,959 


1, 147, 115 
754,610 

1,048,638 
994, 102 

1, 17S,  236 


Board  feet. 
232, 685 
203, 769 
259, 639 
155,  513 
143,307 
119,339 
87,027 

128, 436 
85,723 
118,692 
100,662 
110,996 


15,511,545 


1,745,: 


Includes  both  butt  rot  and  true  redheart.    Tally  for  a  large  representative  mill  m  Clark  County,  Ark. 


38  BULLETIN   244,  U.    S.   DEPARTMENT   OF   AGRICULTURE. 

In  a  year's  forest  cut  of  shortleaf  timber  the  average  loss  by  red- 
beart  was  11  per  cent  of  tbe  total  cut.  Tbe  trees  were  mostly 
between  60  and  180  years  old,  some  being  200  years  old. 

The  wounds  through  which  the  spores  enter  the  tree  are  caused 
partly  by  wind  and  sleet  storms  breaking  the  branches,  but  more 
largely  by  fires,  which  kiU  a  portion  of  the  sapwood,  thus  exposing 
the  heartwood  to  infection.  Thrifty  young  trees  are  to  a  consid- 
erable extent  protected  from  infection  by  the  resinous  exudations 
which  quickly  form  over  wounds.  The  "punk,"  or  fruiting  bodies, 
of  the  fungus  frequently  occur  near  the  place  of  attack,  and,  for  butt- 
rottmg  fungi,  are  usually  located  on  the  lower  half  of  the  trunk. 
The  damage  can  be  very  largely  controlled  by  eliminating  the  chief 
cause — ^fire.  In  the  more  intensive  management  of  small  tracts  of 
timber,  so  far  as  possible  the  diseased  trees  should  be  felled.  The 
removal  from  the  tree  of  the  sporophores,  or  "punks,"  is  of  slight 
temporary  benefit  only,  since  it  stimulates  the  formation  of  new 
fruiting  bodies  at  other  places  on  the  tree. 

Sap  stain,  or  "bluing"  of  the  sapwood,  generally  agreed  among 
investigators  to  be  the  direct  result  of  a  fungus,  is  the  most  per- 
ceptible and  the  most  controllable  form  of  fungous  injury.  The 
reduction  in  value  of  stained  lumber  results  in  enormous  annual 
loss.  Since  moisture  and  heat  are  favorable  to  the  development 
and  spread  of  the  organism,  the  South  suffers  badly,  but  the  pres- 
ence of  resin  in  the  pines  aids  in  checking  the  attack.  In  addition 
to  the  usual  method  of  rapid  drying  of  the  wood,  experiments  have 
been  conducted  in  chemically  treating  the  wood  of  shortleaf  pine 
with  a  view  of  preventing  attack  from  sap-stained  fungi. 

WIND   AND   LIGHTNING. 

Over  the  greater  part  of  its  range,  shortleaf  is  only  slightly  sus- 
ceptible to  wind  damage.  This  is  due  to  its  deep  root  system  and 
its  situation  chiefly  on  the  lighter,  better-drained  soils.  Other  aids 
to  protection  against  wind  are  its  short  loaves,  slender  branches,  and 
narrow  crown.  On  the  other  hand,  shortleaf  is  the  only  pine  that 
extends  well  into  the  tornado  ^  region  of  the  Middle  Western  States. 
Here  considerable  damage  is  done  every  year,  particularly  in  the 
Ozark  uplands  of  Missouri,  Arkansas,  and  Oldahoma.  Strips  of 
wind-thro-svn  forest  are  present  in  all  stages  of  recovery.  After  the 
decay  of  the  thrown  timber  these  are  easily  recognized  by  the  even- 
aged  stand,  usually  of  pure  pine,  in  the  central  area,  with  the  two- 
storied  and  high-forest  condition  in  increasing  degree  toward  the 
margm  of  the  cyclone  strip.  On  account  of  its  quick  response  to 
light  and  the  small  size  and  abundance  of  its  seed,  the  occurrence  of 
tornadoes  has  extensively  aided  the  formation  of  pure,  even-aged 

1  Known  commonly  a.;  "cyclone." 


LIFE    HISTORY    OF    SHORTLEAF    PIXE.  39 

stands  of  pine.  Near  Womble,  on  the  Arkansas  National  Forest, 
is  such  a  fully  stocked,  even-aged  stand  on  a  strip  averaging  approxi- 
mately one-half  mile  in  width  by  14  miles  in  length.  The  tornado 
occurred  on  May  8,  1882,  and  a  large  amount  of  the  young  stand 
dates  from  the  same  spring,  showing  the  coincidence  of  a  heavy  seed 
crop  the  previous  fall  and  favorable  conditions  for  germination. 

Damage  from  ice  storms  is  increased  by  the  effect  of  wind  upon  the 
heavily  laden  trees.  Ice  or  sleet  storms  cause  serious  injury  at 
varying  intervals  of  6  to  12  years.  An  ice  storm  in  December,  1898, 
in  southwestern  Arkansas  uprooted  and  broke  down  so  many  trees 
that  it  completely  blocked  road  traffic  over  all  of  the  timbered  roads 
for  nearly  one  week.  The  damage  from  snow  press  is  relatively 
small. 

Lightning  kills  trees  occasionally  and  injures  very  many.  The 
secondary  injury  from  winds  and  lightning  is  possibly  even  greater 
than  the  direct  effect,  since  injurious  insects  and  fungi  find  their 
chief  avenue  of  attack  in  freslily  opened  wounds  in  the  bark  and 
cambium,  or  living  layer,  of  the  tree. 

YIELD. 

FACTORS   INFLUENCING    YIELD. 

The  growth  of  a  stand  as  a  whole  determines  its  productiveness  or 
yield.  First,  regions  favorable  to  the  greatest  volume  production 
in  the  individual  tree  likewise  produce  the  largest  crops  or  highest 
yields  per  acre  of  timber.  The  yield  of  well-stocked  stands  of 
65-year-old  shortleaf  in  central  North  Carohna  is  much  greater  than 
that  of  stands  of  similar  age  and  density  in  New  Jersey,  and  in  the 
Arkansas-Louisiana  region  not  less  than  20  per  cent  greater  than  in 
North  Carolina.^  Second,  the  number  of  trees  per  acre  affects  directly 
the  size  and  volume  production  of  the  individual  tree  and  of  the  stand, 
and  therefore  the  quality  of  the  yield.  Overstocked  as  well  as 
understocked  stands  decline  rapidly  in  saw-timber  production  as  the 
number  of  trees  departs  in  either  direction  from  the  normal  or  best 
condition  of  stocking.  The  decline  in  total  cubic  volume  is  not  so 
great,  especially  in  fully  stocked  stands.  What  the  conditions  are 
in  any  region  can  be  accurately  determined  by  measuring  stands 
similar  in  all  points  except  the  degree  of  stocking.  One  nearly  always 
finds  wide  differences  occurring  in  respect  to  the  number  of  trees  per 
acre  and  the  corresponding  yields,  both  within  adjacent  stands  and 
in  portions  of  the  same  stand.  Third,  the  yield  varies  with  the  age  of 
the  stand.  The  yield  of  a  stand  rises  with  age  to  a  point  of  maximum 
production,  after  which  there  is  a  decline  due  to  the  progress  of 
natural  thinning  by  the  loss  of  trees  through  declining  vigor  and 

1  This  difference  is  undoubtedly  due  to  regional  differences  in  the  supply  of  atmospheric  and  soil  moisture, 
temperature,  and  the  physical  texture  and  composition  of  the  soil. 


40 


BULLETIN    244,    U.    S.    DEPARTMEXT   OF   AGRICULTURE. 


attacks  of  natural  enemies  of  various  sorts.  In  good  situations  in 
Arkansas,  for  instance,  well-stocked  160-Year-old  stands  of  shortleaf 
have  average  yields  of  about  45,000  board  feet,  or  approximately 
the  same  as  58-year-old  stands  on  similar  situations.  The  point  of 
highest  average  amiual  production  of  natural  unthinned  stands  is 
probably  between  90  and  100  years  in  Arkansas  and  some  10  years 
earher  in  the  central  Piedmont  region  bordering  the  Atlantic  coastal 
plain. 

Table  15. — Relation  between  tree  density  and  yield  -per  acre  for  30-year-old  shortleaf  pine. 

[Yield  from  trees  8  inches  and  over  in  diameter.    Based  on  7  sample  areas  in  Arkansas  in  stands  of  similar 
soil,  protected  against  fires,  and  ranging  from  210  to  780  trees  per  acre  in  quality  I  site.] 


Trees  per  acre. 

Yield  (saw  timber). 

Average 

Total. 

8  inches 
and  overin 
diameter. 

Scribner 
rule. 

?S' 

diameter. 

Feet  b.  m. 

Feeth.m. 

Inches. 

150 

130 

n,250 

6,600 

n.5 

200 

175 

13,500 

8,450 

10.9 

250 

215 

16,000 

9,700 

10.4 

300 

260 

18,100 

10,600 

9.8 

350 

290 

19,400 

10,800 

9.4 

400 

290 

19,100 

10, 200 

8.9 

450 

260 

17,500 

9,000 

8.5 

500 

255 

15,350 

7,900 

8.1 

550 

235 

13, 200 

6.800 

7.7 

600 

215 

11,250 

5,800 

7.3 

650 

195 

9,250 

4,450 

7.0 

700 

180 

7,500 

3,200 

6.6 

750 

160 

5,900 

2,000 

6.3 

800 

140 

4;  250 

800 

6.0 

YIELD   IN   PURE   STANDS. 


Old  growth  or  vhgin  stands  in  regions  of  good  development  show 
yields  averaging  10  to  30  thousand  board  feet  per  acre  over  con- 
siderable areas.  Most  of  such  tracts  are  at  the  present  time  found 
only  in  the  more  inaccessible  regions  in  the  upper  portions  of  the 
middle  Atlantic  coastal  States  and  in  the  Louisiana-Arkansas  district. 
Much  larger  amounts  occur  in  mixed  stands  with  hardwoods. 

Fully  stocked  tracts  of  shortleaf  pine  in  natural  stands  are  scat- 
tered and  rarely  occur  in  areas  of  considerable  size.  Irregular 
stocking  at  the  outset,  fire,  and  other  causes  produce  many  open 
spaces  where  trees  are  needed  to  complete  the  stand.  In  other  places 
the  stand  has  from  the  start  maintained  too  many  trees  per  acre  to 
give  the  best  results  in  quahty  or  c^uantity  of  product.  The  average 
yields  of  natural  stands,  therefore,  vary  widely  and  have  little  sig- 
nificance in  considering  the  habits  and  possibilities  of  the  tree  when 
growing  in  fuU  stands.  The  best  basis  for  considering  the  yield  of 
forest  trees  like  shortleaf  which  occur  in  pure  stands  is  the  yield  of 
fully  stocked  stands  or  portions  of  stands  growing  under  known  con- 
ditions of  situation.  Such  information,  when  classified  by  age  and 
site  quahty  for  normally  stocked  stands,  is  known  as  a  normal  jaeld 


LIFE    HISTORY   OF    SHORTLEAF    PIXE. 


41 


table.  Tables  16,  17,  and  18  have  been  thus  prepared  by  measuring 
portions  of  well-stocked  second-growth  or  old-field  stands  of  known 
age  and  quahty  of  natural  environment,  particularly  character  of  sod 
and  moisture  supply.  For  example,  the  average  yield  of  50-year-old 
stands  on  the  best  class  of  sites  in  North  Carolina  (Table  16)  is  about 
23,700  board  feet,  on  medium  or  average  sites  17,000,  and  on  the 
poorest  sites  about  10,300  board  feet.  Table  18  shows  yields  in  the 
Arkansas  region  at  50  years  of  37,200,  23,750,  and  12,200  board  feet, 
respectively,  on  the  three  quahties  of  site.  The  original  figures  for 
North  Carolina  were  secured  from  80  selected  sample  tracts  with  an 
area  of  21.6  acres^  which  may  be  considered  fairly  representative. 
The  data  for  Table  18  are  insufficient  in  amount,  hence  the  table  is 
tentative  and  has  been  included  for  the  purpose  of  comparison  and 
correction  when  more  measurements  become  available. 

Table  16. —  Yield  of  tvell-stocked  second-grouth  shortleaf  pine  in  North  Carolina.^ 

[Based  on  SO  sample  plots  in  well-stocked  stands;  total  area,  21.6  acres.  Saw  timber  scaled  to  6  inches  in 
top  diameter;  stump  height,  1  to  1.5  feet.  Volume  of  stem  is  from  1-foot  stump  to  6-inch  top  diameter, 
including  bark.    All  trees  6  inches  and  over  diameter  breast  high  were  scaled.] 

QUALITY  I. 


Age  (years). 


Trees 

Average 
diameter 

Average 

Total 
basal 
area. 

per  acre. 

breast 
high. 

height. 

Inches. 

Feet. 

Sq.  ft. 

2,940 

2.8 

22 

104 

1,760 

4.4 

32 

135 

1,000 

5.8 

40 

158 

675 

6.9 

46 

175 

510 

7.9 

51 

188 

410 

8.8 

55 

198 

340 

9.6 

59 

205 

280 

10.4 

63 

211 

235 

11.2 

66 

215 

200 

11.9 

69 

218 

165 

12.7 

72 

220 

140 

13.4 

74 

222 

120 

14.1 

77 

224 

100 

14.7 

79 

226 

90 

15.3 

81 

227 

Yield  per  acre. 


Scribner      Doyle 
rale. 


Doyle 
rale. 


SoUd 
contents. 


10 
15 
20 
25 
30 
35 
40 
45 
50 
55 
60 
65 
70 
75 
80 

10. 
15. 
20. 
25. 
30. 
35. 
40. 
45. 
50. 
55. 
60. 
65. 
70. 
75. 


Bd.ft. 
400 
3,000 
5,700 
8,400 
11,200 
14,000 
17,100 
20,300 
23,700 
27,000 
30,100 
33,200 
36,100 
38,800 
41,500 


Sd.  ft. 


300 
2,000 
3,600 
5,300 
7,100 
8,900 
10,900 
12,800 
14,500 
16,200 
17,700 
19,300 
20,800 
2?, 400 


ft. 
,050 
,560 
,120 
,730 
,350 
,950 
,570 
,200 


QUALITY  II. 


3,725 

2.2 

2,450 

3.4 

1,635 

4.6 

1,095 

5.6 

765 

6.5 

600 

7.3 

500 

8.0 

420 

8.7 

355 

9.4 

310 

10.0 

270 

10.6 

230 

11.3 

205 

11.8 

180 

12.4 

'" 

13.0 

18 

82 

?fi 

108 

1,100 

33 

129 

3,200 

300 

38 

145 

5,200 

1,700 

43 

156 

7,300 

3,200 

47 

165 

9,400 

4  700 

50 

172 

11,700 

6,300 

54 

176 

14,300 

7,900 

57 

179 

17,000 

9,500 

59 

182 

19,700 

11,000 

62 

183 

22,400 

12,500 

64 

185 

25,200 

13,900 

66 

186 

27,800 

15,300 

69 

187 

30,400 

16,700 

71 

188 

32,900 

18,100 

660 
1,000 
1,380 
1,840 
2,330 
2,820 
3,320 
3,830 
4,360 
4,880 
5,360 
5,830 
6,280 
6,730 
7,lfiO 


'  Counties  in  Xorth  Carolina  are:  Alexander,  Burke,  Cabarrus,  Catawba,  Cleveland,  Davie,  G£ 
Lincoln,  McDowell,  Rowan,  Rutherford,  Surry,  Wilkes,  and  Yadkin. 


42  BULLETIN   244,   U.    S.    DEPARTMENT   OF   AGRICULTURE. 

Table  10. —  Yield  of  ivell-stocked  second-growth  shortleaf  pine  in  North  Carolina. — Con. 

QUALITY  III. 


Trees 
per  acre. 

Average 

diameter 

breast 

high. 

Average 
height. 

Total 
area. 

Yield  per  acre. 

Age  (years). 

Saw  timber. 

Solid 

Scribner 
rule. 

» 

contents. 

Inches. 
1.6 
2.5 
3.4 
4.2 
5.0 
5.7 
6.4 
7.0 
7.6 
8.2 
8.7 
9.2 
9.7 
10.2 
10.6 

Feet. 
.   14 
21 
26 
31 
35 
39 
42 
45 
47 
50 
52 
54 
56 
58 
60 

82 
100 
114 
125 
133 
138 
142 
144 
145 
146 
147 
148 
149 
149 

Bd.ft. 

Bd.ft. 

Cu.ft. 
290 

15 

3,270 

2,450 

1,880 

1  405 

1,045 

795 

655 

550 

475 

420 

370 

330 

295 

270 

450 

20 

700 
2,100 
3,400 
4,800 
6,500 
8,300 
10, 300 
12,400 
14,  700 
17,100 
19,  TOO 
22,000 
24,200 

650 

30                                         

1,100 
2,300 
3,600 
4,900 
6,200 
7,500 
8,800 
10,100 
11,400 
12,600 
13,900 

1  290 

35 

1,670 

40         

2,070 

45                        

2  470 

50 

2,880 

55 

3,300 

60         

3,700 

65                                      .... 

4  100 

70 

4,490 

80                           

5,230 

Table  17. —  Yearly  increment  of  second-growth  shortleaf  pine  in  North  Carolina.^ 


[Based  on  80  sample  plots  in  well-stocked  stands;  total  area,  21 
top  diameter.  Stump  height,  1  to  1.5  feet.  Volume  of  stem  i 
including  bark.    All  trees  6  inche 


acres.    Saw  timber  scaled  to  6  inches  in 
is  from  1-foot  stump  to  6-inch  top  diameter, 
over  diameter  breast  high  were  scaled.] 


PERIODIC  ANNUAL  INCREMENT. 


Scribner  rule. 

Doyle  rule. 

SoUd  contents. 

Age  (years). 

Quality 

Quality 
II. 

Qu^aUty 

Quality  Quality 

Qujji.. 

Quality 

^uaUty 

«i?r 

Bd.  ft. 
500 
530 
560 
590 
620 
650 
680 
655 
625 
605 
580 
560 
540 

Bd.  ft. 
370 
400 
430 
460 
485 
505 
525 
540 
550 
560 
545 
520 
490 

Bd.ft. 

""246' 
275 
310 
340 
370 
400 
425 
455 
475 
500 
475 
445 

Bd.  ft. 
300 
320 
340 
360 
380 

Bd.  ft. 

Bd.ft. 

Cu.ft. 
112 
117 
121 
124 
126 
127 
128 
123 
117 
112 
106 
100 
94 

88 
93 
98 
101 
104 
106 
104 
101 
97 
92 
87 
82 

Cu.„^ 

280 
295 
310 
315 

""2iCi 
250 
255 
255 
260 
260 
260 
260 
255 
250 

59 

30          

66 

35                                        

72 

40 

76 

400         3'20 

80 

50                      

380 
365 
350 
330 
315 
300 
285 

315 
310 
300 
290 
280 
275 
265 

82 

55 

84 

60           

83 

65           

81 

70                                        

78 

75 

75 

71 

MEAN  ANNUAL  INCREMENT. 


20           

285 
335 
370 
405 
430 
450 
470 
490 
500 
510 
515 
520 
520 

175 
205 
240 
270 
295 
320 
340 
360 
375 
385 
395 
405 
410 

50 
80 
110 
135 
160 
185 
205 
225 
245 
260 
275 
295 
310 

100 
140 
175 
205 
225 
245 
255 
265 
270 
275 
275 
280 
280 

15 
65 
105 
135 
160 
175 
190 
200 
210 
215 
220 
225 
225 

35 
65 
90 
110 
125 
135 
145 
155 
165 
170 
175 

107 
109 
111 
113 
115 
116 
117 
117 
117 
116 
116 
115 
114 

69 

74 
78 
81 
83 
85 
87 

89 
90 
90 
90 
90 

32 

38 

30                         

43 

35 

48 

52 

55 

50                                    

58 

55 

60 

62 

66                    

70                                      

64 

75 

65 

65 

1  Counties  in  North  Carolina  are:  Alexander,  Burke,  Cabarrus,  Catawba,  Cleveland,  Davie,  Gaston, 
Lincoln,  McDowell,  Rowan,  Rutherford,  Surry,  Wilkes,  and  Yadkin. 


LIFE    HISTORY   OF    SHORTLEAF    PINE. 


43 


Table  18. —  Yield  of  second-growth  shortleaf  pine  in  Arkansas. 

[Based  on  38  fully  stocked  sample  plots;  area,  5.8  acres.    All  trees  6  inches  and  over  in  diameter  breast 
high  were  scaled.    Top  diameter,  5.5  inches:  stumpheight,  1  foot;  numberof  trees  per  acre,  see  page  17.] 

QUALITY  I. 


20 
2,^ 
30 
35 
40 
45 
50 
55 
60 
65 
70 


Average 
height 
of  tree. 


Average 
diameter 

6  inches 
and  over. 


Incites. 
7.5 
8.6 
9.6 
10.6 
11.4 
12.2 
13.0 
13.6 
14.2 
14.8 
15.3 
1.5.8 
16.2 


Total 

basal  area 

(breast 

high)  per 


Sg.  ft. 


Yield  per  acre. 


Scribner 
rule. 


Bd.  ft. 
8,000 
12,700 
17,500 
22,  400 
27,  500 
32,500 
37,400 
42,  200 
46,850 
51,350 
55,750 


Doyle 
rule. 


£d.  ft. 


4,200 
6,600 
9,700 
13,  400 
17,600 
21,800 
25,  600 
29,000 
32, 100 
35,000 
37,  800 
40,500 


Total 
volume. 


Cm.  ft. 
2, 500 
3,630 
4,900 
6,060 
7,010 
7,730 
8,320 
8,850 
9,320 
9,760 
10, 160 
10,  ,'-.20 
10,  8.50 


QUALITY  II. 


20 
25 
30 
35 
40 
45 
50 
.55 
60 
65, 
70 
75 


6.6 
7.5 
8.3 
9.1 
9.9 
10.7 
11.3 
12.0 
12.5 
13.1 
13.6 
14.1 
14.5 


4,350 
7,450 
10,600 
13,800 
17,000 
20,200 
23, 450 
26,  850 
30,  600 
34,  050 
37, 500 
40,  850 
44,000 


2,700 
4,500 
6,800 
9,  .500 
12,400 
15,400 
18,200 
20,  600 
23,000 
2;5,  200 
27,  400 
29,500 


2,520 
3,390 
4,220 
4,930 
5,520 
6,050 
6,520 

7^410 
7,800 
8,160 
8,500 


QUALITY  III. 


8.4 

9!  7 
10.3 
10.8 
11.4 
11.9 
12.4 
12.9 


2,600 
4,300 
6,000 
7,900 
10, 000 
12,200 
14,  600 
17, 100 
19,600 
22, 000 
24, 600 
27,100 


1,200 
2,500 
3,900 
5,500 
7,200 
9,000 
10,  600 
12,300 
13,  900 

15,  400 

16,  900 
18, 400 


2,360 
2,850 
3,310 
3,760 
4,210 
4,650 
5,070 
5,450 
5,810 
6,150 


44  BULLETIN    244,   T'.    S.    DEPARTMENT   OF   AORICULTURE. 

SCOTCH   AND   SHORTLEAF   PINES. 

In  a  number  of  silvical  features  Scotch  pine  {Pinus  syhestris)  and 
shortleaf  pine  appear  to  be  quite  similar. 

'  Both  trees  belong  to  the  two-leaved  group  of  pines  ^  and  form 
close  stands  made  up  of  tall  stems,  free  from  branches  for  two-thirds 
of  their  length  and  termmating  in  short  compact  crowns.  Both  are 
vigorous  and  hardy  growers  and  not  subject  to  any  markedly  serious 
parasitic  fungous  disease.  Wliile  both  species  are  adapted  to  the 
drier  type  of  soil  occurrmg  on  the  uplands,  they  differ  m  belonging 
characteristically  to  different  zones  of  climate.  Scotch  pine  does 
not  require  nearly  so  much  heat  during  the  summer  and  will  endure 
much  lower  temperatures  than  shortleaf  in  winter.  The  seeds  of 
both  appear  practically  the  same  m  size  and  general  vigor,  and  both 
species  are  readily  grown  in  the  nursery.  Shortleaf,  however,  regen- 
erates itself  by  sprouting  from  the  stump,  inherently  possesses  a 
much  straighter  stem,  has  smaller-sized  branches,  and  cleans  itself 
more  quickly  in  stands.  Fully  stocked  stands  of  Scotch  pine  at  any 
specified  age  contain  a  greater  number  of  trees,  although  of  smaller 
size  than  shortleaf  pine  indicating  a  somewhat  greater  degree  of 
tolerance. 

All  measurements  of  yield  show  considerably  larger  returns  from 
shortleaf  than  from  Scotch  pine.  The  maximum  average  annual 
growth  per  acre  of  shortleaf  pine  on  the  best  quality  sites  m  North 
Carolina  is  117  cubic  feet  at  the  age  of  55  years;  that  of  Scotch  pme 
m  Germany,  about  90  cubic  feet  at  55  years.  These  maximum  yields 
range  downward  on  the  poorest  quality  sites  to  65  cubic  feet  at  80 
years  for  shortleaf  pine  and  about  40  cubic  feet  for  Scotch  pme  at 
65  years.  Weise's  table  for  Scotch  pine  is  based  upon  351  sample 
tracts  located  in  5  German  States,  while  the  shortleaf-pme  table  shows 
the  results  of  only  80  sample  tracts  located  in  14  counties  in  North 
Carolma.  Table  19  shows  several  points  of  likeness  and  unlikeness 
in  these  two  pines.  The  shortleaf  data  are  not  so  representative  of 
the  species  as  that  for  Scotch  pme.  The  German  plots  were  all  normal 
stands,  last  thmned  just  prior  to  the  measurement,  while  the  North 
Carolina  shortleaf  plots  were  average  well-stocked  natural  untreated 
stands  in  old  fields,  thinned  somewhat  by  the  action  of  fires.  Under 
these  unUke  conditions  the  results  can  not  be  fairly  comparable,  but 
may  be  taken  as  an  indication  of  the  character  and  possibilities  of 
the  two  pines. 

In  respect  to  height,  shortleaf  pine  leads  under  all  conditions  of 
age  and  situation,  but  the  difference  is  most  marked  during  about 
the  first  30  to  40  years,  and  on  the  poorer  sites  at  all  ages  up  to  80 
years. 

I  Shortleaf  varies  to  three  leaves  in  the  bundle  on  the  vigorous  growing  parts  of  the  crown. 


LIFE    HISTORY   OF    SHORTLEAF   PIXE.  45 

Table  19. —  Yield  of  shortleuf  pine  in  North  Carolina,  compared  uilh  yield  of  Scotch 
pine  in  Germany.  ^ 


Characters  compared. 


Scotch  pine. 


Quality  Quality  Quality 
I.      I     II.         III. 


Trees  per  acre: 

Trees  30  years  old 

Trees  50  years  old 

Trees  80  years  old 

Diameter,  breast  high  (inches): 

Trees  30  years  old 

Trees  50  years  old 

Trees  80  years  old 

Basal  area,  breast  high,  total  ijer  acre  (square  feet): 

Trees  30  years  old 

Trees  50  years  old 

Trees  80  years  old \ 

Height,  average  (feet): 

Trees  30  years  old 

Trees  50  years  old 

Trees  80  years  old 

Yield,  total  per  acre  (cubic  feet):  -  I 

Trees  30  years  old :    1 


1,543 
590 
206 

4.0 
7.3 
11.5 

130 

167^ 

184 


Trees  50  years  old 

Trees  80  years  old 

Periodic  armiial  increment  (culjic  feet): 

Trees  30  years  old 

Trees  50  years  old 

Trees  80  years  old 

Mean  annual  increment  (cubic  feet): 

Trees  30  years  old 

Trees  50  years  old 

Trees  80  years  old 


4, 500 
6,570 


2,  .5:36 

758 
317 


2,700 
4,260 


67 
108 
132 

21 
34 

48 

400 
1,730 
2,930 


Shortleaf  pine. 


Quality  Quality  Quality 
I.  11.         III. 


7.9 
11.2 
15.3 


215 
227 

51 
66 
81 

3,350 
5,850 
9,100 

121 
128 

94 

111 
117 
114 


7e55 
355 
1.55 

6.5 
9.4 
13.0 

156 
179 

188 

43 

57 
71 

2,350 
4,350 
7,150 


1,4U5 
5.50 
270 

5.0 
7.6 
10.6 

125 
144 
149 


1,.300 
2,900 
5,250 


1  Figures  from  Weise's  yield  tables  for  Scotch  pine.  Quality  I  and  II  averaged  to  make  I;  III  taken  as  II; 
and  IV  and  V  averaged  to  make  Quality  III. 

-  Yield  of  Scotch  pine  taken  for  all  wood  down  to  3  inches  in  diameter;  of  shortleaf  pine  taken  only  for 
trees  up  to  6  inches  diameter  breast  high,  and  to  6  inches  in  tops. 

The  superiority  of  shortleaf  over  Scotch  pine  in  size  of  trees  and 
total  yield  is  striking.  Scotch-pine  stands  contain  from  two  to  three 
times  as  many  trees  per  acre  as  the  shortleaf  stands,  and  the  trees 
have  correspondingly  smaller  average  diameters.  A  comparison  of 
the  total  yield  of  the  two  species  is  interesting.  At  the  age  of  30 
years  shortleaf  shows  about  two  or  three  times  the  yield  of  the  Scotch 
pine  for  the  better  and  poorer  sites,  respectively.  At  50  yeai-s  on 
fii-st  quality  situations,  the  two  species  approach  the  closest  in  yield, 
yet  the  yield  of  shortleaf  is  just  30  per  cent  gi"eater  than  that  of 
Scotch  pine.  The  shortleaf  yield  is  again  about  56  per  cent  greater 
at  the  age  of  80  years.  Similar  yield  tables  for  Scotch  pine  by  Dr. 
Schwappach  show  usually  from  15  to  20  per  cent  less  yield  than 
Weise's  tables. 

YIELD    IN    MIXED   STANDS. 

In  mixed  pine  and  hardwood  stands  the  yield  of  shortleaf  varies 
widely.  In  the  lower  mountains  of  northern  Georgia  recent  timber 
estimates  made  by  the  Appalachian  surveys  show  an  average  yield 
of  1,000  to  3,000  board  feet  per  acre;  but  on  the  warmer  slopes  in 
the  same  region,  pure  vu-gm  pine  stands  of  mixed  ages  covering 


46  BULLETIX    244,    U.    S.    DEPARTMENT    OF    AGRICULTURE. 

several  hundred  acres  yield  from  12,000  to  20,000  board  feet  per 
acre. 

Hundreds  of  square  miles  of  the  better  shortleaf  forests  mixed 
with  oak  and  hickory  over  central  and  western  Arkansas  and  adjacent 
parts  of  Oklahoma  and  Louisiana  wiU  cut  an  average  of  about  5,000 
board  feet  of  shortleaf.  The  character  of  the  forests  in  the  more 
mountainous  parts  of  Arkansas,  where  shortleaf  is  confined  chiefly 
to  the  flats  and  warm  south  slopes,  is  seen  in  Table  2,  showing  the 
composition  of  the  forest  cover  in  the  Arkansas  and  Ozark  National 
Forests.  In  the  higher  hilly  region  of  the  Arkansas  National  Forest, 
cutting  to  an  approximate  diameter  limit  of  14  inches  breast  high, 
or  about  15  mches  on  a  1-foot  stump,  the  pine  in  the  mixed  type 
commonly  yields  about  2,000  board  feet  ^  of  merchantable  timber 
per  acre,  leavmg  about  1,000  feet  for  seed  trees  and  second  cut. 

The  average  run  in  private  cutting,  down  to  a  12-inch  stump 
diameter  limit,  is  10  logs  per  thousand  board  feet.  In  a  representative 
sale  on  the  Arkansas  National  Forest,  cutting  to  a  14-inch  diameter 
limit  at  breast  height,  the  logs  averaged  135  feet  each,  or  8  logs  per 
thousand.  The  bulk  of  the  timber  cut  ranged  from  60  to  180  years 
old.  The  oldest  good-sized  groups  or  small  stands  observed  over  a 
wide  district  in  central  Arkansas  were  170  to  180  years,  and  a  large 
number  of  them  were  found  throughout  the  whole  region.  The 
yields  of  these  groups  or  smaU-sized  stands  ranged  mostly  between 
25,000  and  35,000  board  feet  per  acre,  and  the  maximum  acre  meas- 
ured was  62,000  board  feet.  In  Montgomery  County,  Ark.,  a  com- 
pany recently  cut  2,500  feet  per  acre  (Doyle  log  scale),  or  an  actual 
mill  cut  of  nearly  4,000  feet  of  lumber  per  acre,  from  a  private  tract 
of  4,000  acres  in  the  high  hiUy  country  within  the  Arkansas  National 
Forest.  The  best  cut  of  this  company  was  910,560  (Doyle  scale)  on 
160  acres,  or  an  actual  miU  cut  of  somewhat  better  than  1,500,000 
feet,  an  average  of  approximately  9,500  feet  per  acre. 

1  Based  upon  growth  and  reproduction  plots  on  the  Arkansas  National  Forest  in  average  cut-over 
tracts,  1912. 


II 


